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QSORT -- Version 3.22 QSORT -- Version 3.22 Text File Sorting Utility Text File Sorting Utility Copyright 1985, 86, 87, 88 - Ben Baker Copyright 1985, 86, 87, 88 - Ben Baker All rights reserved All rights reserved Table of Contents Table of Contents Introduction 1 About Shareware 1 Notation 2 The QSORT Command and Options 3 The /<key_spec> Parameter 4 The /F<len> Parameter 5 The /T[<tag>] Parameter 5 The /D[<fields>][<delim>[<term>]] Parameter 6 The /R Parameter 7 The /S[V] Parameter 7 The /? Parameter 9 The "2><error_file>" parameter 9 Lexicographic Sorting 11 Examples 12 Error Messages and Return Codes 14 Command Line Errors 15 Memory Errors 16 I/O Errors 17 Internal Errors 17 ERRORLEVEL Return Codes 18 Implementation Notes 18 General Information 18 Performance and DOS Configuration 19 Performance and Input Record Type 21 Performance and Sort Keys 22 Performance and File Size 23 i Introduction Introduction QSORT was first designed to be a replacement for, and to overcome the limitations of DOS SORT, but has been enhanced a number of times and moved to new compilers twice. The current version will sort files whose size is limited only by available disk space. File name(s) may be given explicitly or QSORT will sort from standard input to standard output, and so, may be used in pipes or with redirection. Multiple keys may be specified. Binary files with fixed-length records may be sorted, provided only that keys are ASCII character strings. QSORT tries to be very protective of your data. If QSORT has an error of any kind, it will terminate with the input file still intact, and will return to DOS with a non-zero ERRORLEVEL. When QSORT successfully completes sorting a file, it terminates with ERRORLEVEL set to zero. The command line syntax is a super-set of DOS SORT's syntax, so QSORT may be used without other changes in batch files using SORT, but in most cases you will probably want to make use of QSORT's greater capabilities. About Shareware About Shareware QSORT is the copyrighted property of Ben Baker. It is dis- tributed under a license agreement with System Enhancement Asso- ciates, Inc. (SEA), and is made available under the "shareware" concept. Shareware products are distributed freely and publicly. You are invited to "test drive" them without cost. But shareware is NOT FREE! If you use a product, you are expected to pay a fee for its use. Because overhead costs are lower, this fee is usu- ally a fraction of the normal commercial price the product might carry, but it is NOT zero! Both the author and SEA believe in the shareware concept. We are both opposed to the "crippleware" concept used by some authors, by which a severely limited version of the product is distributed publicly, and the user must register in order to receive a func- ____ tional version. At the same time, we feel the user should be of- fered more incentive than mere guilt to register a shareware product. We have therefore adopted a policy of withholding the latest ma- jor release of the QSORT program from shareware, and marketing it only as a commercial product. As of this writing, version 3.22 of the QSORT program is shareware and version 4.00 (see the ac- companying history file) is a commercial product. When version 5 is created, the latest release level of version 4 will become QSORT Text Sorting Utility 2 shareware, etc.. Hence, the version of QSORT you receive as shareware is fully functional and fully documented. It is just not the latest version available. If you find this program useful, non-commercial users are asked to pay a license fee of $20 for each machine on which it is used. The license fee for commercial use of QSORT is $35 for the first machine. Liberal quantity discounts, and site licensing are available. On receipt of your registration fee, you will be sent a diskette containing the latest commercial version of the QSORT program ___ ______ with on-disk documentation. The complete commercial packagge, including printed documentation and technical support is $50. This version of QSORT may be freely copied and distributed, pro- vided that 1) it is distributed under the name "QSORT," and 2) the documentation file always accompanies it. Vendors wishing to distribute QSORT as a part of commercial prod- ucts may contact the author's representatives at the address be- low for terms. Send checks or correspondence to: System Enhancement Associates, Inc. 21 New Street Wayne, NJ 07470 Phone: (201) 473-5153 Notation Notation In defining the command line and its various parameters, the following notation is used: [<optional>] items are enclosed in square brackets. [<optional>] __________ <variable> items appear in lower case, underscored, and are <variable> __________ ___________ surrounded by angle brackets (<>). They are replaced by actual data such as a file name. THIS | THAT Choices are separated by a vertical bar. THIS | THAT Select one or the other but not both. [THIS | THAT] When the choices are enclosed in square [THIS | THAT] brackets, they are optional. You need not select either. REPEAT. . . The ellipsis (. . .) means the item to its left REPEAT. . . may be repeated as many times as necessary. QSORT Text Sorting Utility 3 UPPER CASE items and all special characters not defined UPPER CASE above represent themselves. They are entered exactly as they appear. EXAMPLES are shown in bold upper case characters. EXAMPLES bold The QSORT Command and Options The QSORT Command and Options QSORT is invoked with the following command: QSORT [<in_file>[<out_file>]] [/<key_spec>]. . . QSORT [<in_file>[<out_file>]] [/<key_spec>]. . . _________ __________ __________ [/F<len> | /D[<fields>][<delim>[<term>] | [/F<len> | /D[<fields>][<delim>[<term>] | _____ ________ _______ ______ /T[<tag>]] [/R] [/S[V]] [/?] "[2><error_file>]" /T[<tag>]] [/R] [/S[V]] [/?] "[2><error_file>]" _____ ____________ Note that all parameters on the command line are optional. The <in_file> and <out_file> parameters are "ASCII-Z" file speci- _________ __________ fiers. They may contain disk and path information in the stan- dard DOS format, but must not contain "wild-card" characters. If <in_file> is missing, QSORT sorts from standard input to standard _________ output. These are files defined and opened by DOS before QSORT is loaded. (See your DOS manual concerning the use of redirec- tion and pipes.) If <in_file> is given but <out_file> is missing, QSORT creates a _________ __________ temporary file in the directory containing <in_file> and sorts to _________ the temporary file. On successful completion of the sort, <in_file> is deleted and the temporary is renamed to <in_file>. _________ _________ The effect is an apparent "sort-in-place." If both file names are given, <in_file> is unchanged and the _________ sorted output is written to <out_file>. Note that the following __________ two commands are exactly equivalent: QSORT FILE.TXT FILE.SRT QSORT FILE.TXT FILE.SRT QSORT <FILE.TXT >FILE.SRT QSORT <FILE.TXT >FILE.SRT In the first, QSORT opens the files. In the second, redirection is specified and DOS opens the files. The result is the same. It is an error QSORT can't detect if you mix these. For in- stance: QSORT FILE.TXT >FILE.SRT QSORT FILE.TXT >FILE.SRT will result in a sort-in-place. QSORT will open FILE.TXT but won't know DOS has opened FILE.SRT for it, and will ignore it. QSORT Text Sorting Utility 4 The /<key_spec> Parameter The /<key_spec> Parameter __________ Up to 30 /<key_spec> parameters may be used to specify sort keys / __________ and are ordered major to minor from left to right. The /<key_spec> argument has the form: / __________ /[L][+|-][<field>.][<col>][:<length>] /[L][+|-][<field>.][<col>][:<length>] _______ _____ ________ Note that all elements of this argument are "optional," but at least one element must be present following the slant-bar (/). (/) The 'L', if present, specifies "lexicographic" sequence for this 'L' key. Lexicographic sequence is ordered first by spelling, then, when keys have identical spelling, by capitalization. The minus (-) sign reverses the sorting order for this key, while - the plus (+) sign (or no sign) specifies normal sort order. + There are three numbers associated with every sort key: the field number, the starting column within the field, and the length of the key in characters. Any, or all of them may be given in a /<key_spec> parameter. QSORT uses punctuation to identify each / __________ number. A number followed by a period (.) is a field number. A . number preceded by a colon (:) is a length number. A column num- : ber has no punctuation associated with it. It follows the field number, if any, and precedes the length number, if any. The [<field>.] element is used only for "delimited-field" [ .] _______ records, and locates this key within a particular field. The value of <field> must be less than or equal to the number of _______ fields defined with the /D parameter (see below). If [<field>.] /D [ .] _______ is omitted when sorting delimited-field records, the first field is assumed. For consistency, all records are assumed to have "fields." In all cases except delimited-field records, there is precisely one field, and it spans the entire record. If present, [<col>] defines the beginning column of the key. If [ ] _____ omitted, column 1 is assumed. In the case of delimited-field records, column 1 is the first character of the identified field. In all other cases, column 1 is the first character of the record. If present, [:<length>] defines the key length in columns (or [: ] ________ characters). If [:<length>] is omitted, the rest of the record, [: ] ________ or field in delimited-field records, is assumed to be part of the key. If no key parameters are given, the entire record, or the entire first field is the key. When sorting variable-length records, any key which begins beyond the end of its field in a particular record is treated as a null (zero length) key for that record, and will sort low relative to all records with non-null values for that key. When sorting QSORT Text Sorting Utility 5 fixed-length records, all defined keys must fall within the de- fined record length. <key_spec> parameters must appear in order __________ of importance, primary key first. The /F<len> Parameter The /F<len> Parameter _____ The /F<len> parameter denotes the record length for a file of /F _____ fixed-length records. All records in the input file MUST be ex- actly <len> bytes long. The records need not (but may) be termi- _____ nated with a CR/LF sequence. They may contain any data, even bi- nary data, but the keys must be ASCII strings. Strings may be terminated with a null (binary zero) character, or may be padded with trailing spaces to the full length of the key. Note that QSORT does not attempt to support Pascal style strings. These are strings which begin with a character whose binary value is a character count. This is followed by <count> characters of _______ ASCII data, which in turn is followed by random data out to the maximum length of the string. These strings may be used as keys, but the programmer must insure that either the last real charac- ter is a null character, or the key is padded to its full length with spaces. QSORT must be told that the key begins in the sec- ond character position (the first character of real data). The /T[<tag>] Parameter The /T[<tag>] Parameter _____ The /T[<tag>] parameter, if present, indicates that the "records" /T[ ] _____ to be sorted may be more than a single line long. If <tag> is also present, it defines a character to be used to _____ tag the "end-of-record." If <tag> is not present, the first _____ empty line terminates the record. For this purpose, "empty" means "no characters." A line containing but a single space is not empty! A line may be "tagged" by placing the <tag> character ___ _____ anywhere on the last line of a logical record. The entire line, including the tag character will appear as the last line of the record. Some characters cannot be used to represent themselves in a DOS command line. For that reason, QSORT uses codes to represent them. These codes are actually a pair of characters. The first is always a back-slash (\). The second character identifies the QSORT Text Sorting Utility 6 special character it represents. The following is a table of characters recognized by QSORT: \B - Space character \B \F - Form feed character \F \L - Line feed character \L \N - Newline sequence \N \R - Carriage return \R \T - Tab character \T \/ - The slant bar character \/ \\ - Back-slash character itself \\ Thus an invisible tab character might be used to end a multi-line logical record. The other characters in this code list don't make much sense in this context, but will be useful in the /D /D parameter (see below). Notice that the slant bar (/), when used / as a delimiter character in the /T or /D parameters, must be pre- /T /D fixed by the back-slant to prevent it from being interpreted as the beginning of a new parameter. Note that the /F<len> and /T[<tag>] parameters are incompatible, /F /T[ ] _____ _____ and may not both be specified. The /D[<fields>][<delim>[<term>]] Parameter The /D[<fields>][<delim>[<term>]] Parameter ________ _______ ______ The /D[<fields>][<delim>[<term>]] parameter, if present, states /D[ ][ [ ]] ________ _______ ______ that this file contains delimited-field records. In other words, a record is made up of distinct, variable length fields separated from one another by a particular character, or "delimiter." Records are separated, or "delimited" by the "newline sequence." The <fields> element defines the number of variable length fields ________ contained in each record. All fields must be present in each and every record. A "null" field will be represented by two succes- sive delimiter characters. There must always be exactly <fields> ________ minus 1 delimiter characters in a record. If a <delim> character is present, QSORT uses it as a field de- _______ limiter character. Otherwise a comma (,) is assumed to be the delimiter. If a <term> character is also present, QSORT uses it as a record ______ delimiter character. In fact, it literally redefines the "newline sequence" to QSORT. More on this in a moment. The same character codes listed under the /T parameter may be /T used to represent these characters. Note that "\N" means the "\N" "newline sequence." If <term> is not present, this is the CR-LF ______ character pair. If <term> is present, it represents the <term> ______ ______ character. Thus: QSORT Text Sorting Utility 7 /D3\N\T /D3\N\T says that the newline sequence is a tab character, and that the three fields within each record are also separated by tab characters. On the other hand: /D3\N /D3\N says that fields are separated by the newline sequence, thus each group of three lines constitutes one logical record, and each line is a field within that record. The /D parameter is always incompatible with the /F parameter, /D /F and usually incompatible with the /T parameter, but there is an /T exception when <fields> is missing, or is equal to 1. ________ If <fields> equals 1 (or is missing) it says that there is only ________ one field spanning the entire record. But that is what QSORT as- sumes if the whole /D parameter is missing! So why bother? /D In most ASCII files a "line" ends with a carriage return charac- ter (CR) followed by a line feed character (LF). QSORT searches for this character pair when it is looking for a "newline se- quence." But not all files use CR-LF as a line terminator. For instance, files imported from UNIX or XENIX usually terminate lines with a naked line feed character! And some editors produce files whose lines end in a naked carriage return character! So: /D,\L /D,\L says "for this file, the newline sequence is a single line feed character." In this case, the comma is a place holder. There really is no "delimiter character," but one must be present in the parameter in order to define the <term> character. ______ The /R Parameter The /R Parameter The /R parameter is included for compatibility with DOS SORT and /R is redundant. It reverses the sense of sort direction for all sort keys. The /S[V] Parameter The /S[V] Parameter The /S parameter tells QSORT to make a statistics report to the /S screen at the end of a run. The report is written to the "standard error" device, the console, and may not be redirected. The following is an actual statistics report "cut" from the screen after QSORT had sorted a 1.3+ megabyte file: QSORT Text Sorting Utility 8 12115 records sorted 150 bytes in longest record 127131 sort phase comparisons 73232 merge phase comparisons 200363 total comparisons 16.5 comparisons per input record 27 temporary merge files created 2 merge passes 2.4 average passes over data 2:51 elapsed time The first two numbers are self-explanatory. The next two are the number of times two records were compared during the sort phase and the merge phase respectively, followed by the total compar- isons. The next number is total comparisons divided by the number of records in the input file. If there is no merge phase, this num- ber is typically 10 to 12. If the file is large enough to re- quire merging, it is 12 to 20, on average. If it is much larger than 20, it usually means that there is something unusual about your input file. It may already be sorted, or there may be large blocks of records which compare equal. This can happen if you sort on, say column 50 and the input file contains a large number of records shorter than 50 bytes. In this case, a minor sort key at column 1 may significantly speed sorting. The next two items are self-explanatory. "Average passes over data" reflects the number of times each record was read and writ- ten. For short files not requiring a merge pass, this number will be 1.0. When merging is needed, the last merge pass is the one which writes the output file and it must read and write every record exactly once. Thus when only one merge pass is made, there will be exactly 2.0 "average passes over data." In the above case the first merge pass processed about 40% of the records, hence the value of 2.4. The above sort was performed on a Zenith 248, an eight megahertz AT clone with two hard drives (C and D). The input file was on C; the temporary merge files were placed on D; and the output file was written to C:. The sort of a 1.3 megabyte file took un- der three minutes. The same sort on an XT should take about seven minutes. The optional subparameter, [V] (for verbose), causes the QSORT [V] program to make running progress reports to the screen. Each pass during both the sort phase and the merge phase (if any) is- sues a 1-line report telling the merge file(s) and the number of records being processed during that particular pass. This is not terribly useful for short files, but for the big ones, it can QSORT Text Sorting Utility 9 give the user a warm comfortable feeling that something is actu- ally being done. The /? Parameter The /? Parameter The /? parameter requests help or parameter evaluation. When /? QSORT is executed with the /? parameter alone, it lists a short /? description of the QSORT parameters. If /? is entered as one of /? several parameters, QSORT will produce a short report on the screen describing the sort it would perform based on those param- eters without actually doing a sort. For example: QSORT /? /L5:12 /-3:2 /22 /T /R <INFILE.TXT >OUTFILE.TXT QSORT /? /L5:12 /-3:2 /22 /T /R <INFILE.TXT >OUTFILE.TXT produces the following screen report: With the present arguments, QSORT would sort from STDIN to STDOUT Records are multiple lines ending with an empty line Key fields in descending order of importance are: Field Pos Len Type 1 5 12 Lexical Descending 1 3 2 ASCII 1 22 65535 ASCII Descending This display lists everything QSORT knows about the proposed sort. It shows the file name(s), if known, or in this case, the fact that QSORT is being used as a "filter" and file names are unknown. It lists file characteristics, here showing that the input file has records "tagged" with an empty line. And it lists characteristics of all defined key fields. The third key in this report has an unspecified length. The value "65535" merely means that this key extends to the end of each record. The "2><error_file>" parameter The "2><error_file>" parameter ____________ The QSORT program writes its messages and help and statistics screens to the DOS standard error device. DOS allows the user to redirect standard input and standard output, as discussed ear- lier, but makes no provision for redirecting standard error. As far as DOS is concerned, error messages belong on the screen and nowhere else! The "2><error_file>" parameter provides the capability of "2> " ____________ redirecting QSORT's messages and screens to the file named in <error_file>. UNIX users should recognize the syntax immedi- ____________ ately. It is borrowed from the Bourne-Shell. Some replacements for DOS' COMMAND.COM, such as Polytron's PloyShell, also support QSORT Text Sorting Utility 10 this syntax. The parameter should be enclosed in qupte marks as shown to prevent later versions of DOS from trying to perform the redirection wrong! wrong _____ Two variations on this parameter are also recognized by the QSORT program. "2>><error_file>" tells QSORT to open <error_file> in "2>> " ____________ ____________ append mode and add the messages for this run to the end of the contents already in <error_file>. 2>&- turns off all message 2>&- ____________ output from QSORT. A space may be inserted in front of <error_file>, and if the file ____________ name begins with an ampersand (&), a space must precede it to ____ avoid confusion with the last form above and generating an error. To summarize: QSORT JUNK /S "2>MESSAGES.TXT" QSORT JUNK /S "2>MESSAGES.TXT" sorts the file JUNK in place, writing the statistics screen to the file MESSAGES.TXT. If that file already exists, it is re- placed by the output of this QSORT run. QSORT JUNK /S "2>>MESSAGES.TXT" QSORT JUNK /S "2>>MESSAGES.TXT" sorts the file JUNK in place, appending the statistics screen to the end of the file MESSAGES.TXT. QSORT JUNK /S "2>&-" QSORT JUNK /S "2>&-" sorts the file JUNK in place. The /S parameter is meaningless, /S since the "2>&-" parameter turns off all message output from "2>&-" ___ QSORT! The /M<len> supported in earlier versions of QSORT is no longer /M _____ required, but will be accepted (and ignored) by QSORT. There is no "hard-coded" maximum record length in QSORT, but there is a practical limit. At some time during every sort, the two longest records in the input file must be compared. Therefore, the two longest records must be able to fit together in the sort buffer. The sum of their lengths cannot exceed about 50K -- not an alto- gether unreasonable limitation. QSORT can be shoe-horned into tighter memory and will run if it can find 4K for a sort buffer and 4K for an output buffer, but the two longest records must still fit in the sort buffer together. Arguments may appear in any order on the command line except that <in_file> must appear before <out_file>, and /<key_spec> argu- / _________ __________ __________ ments must appear in descending order of importance. QSORT Text Sorting Utility 11 Lexicographic Sorting Lexicographic Sorting The lexicographic sorting capability was born out of my own need to sort word lists with mixed capitalization. ASCII sequence produced some bizarre results when words beginning with 'Z' sorted before those beginning with 'a.' Case-insensitive sorting wasn't much better because upper and lower case got mixed randomly. The following table will illustrate what I mean: INPUT ASCII CASE LEXICO- INSENSITIVE GRAPHIC DeLaPort Baker Baker Baker DeLaPort Baker Baker Baker Smith Brown brown Brown Smith Brown brown Brown brown DeAngelo bRown bRown brown DeAngelo bRown bRown deLaPorte DeLaPort Brown brown deLaPorte DeLaPort Brown brown Deangelo Deangelo Deangelo DeAngelo Deangelo Deangelo Deangelo DeAngelo deAngelo Deangelo deangelo Deangelo deAngelo Deangelo deangelo Deangelo Brown DelaPort Deangelo Deangelo Brown DelaPort Deangelo Deangelo smith DelaPorte deAngelo deAngelo smith DelaPorte deAngelo deAngelo delaPorte Harry DeAngelo deangelo delaPorte Harry DeAngelo deangelo DelaPort Smith delaPort DeLaPort DelaPort Smith delaPort DeLaPort DeAngelo bRown DelaPort DelaPort DeAngelo bRown DelaPort DelaPort DelaPorte brown delaPort delaPort DelaPorte brown delaPort delaPort deangelo deAngelo DeLaPort delaPort deangelo deAngelo DeLaPort delaPort Harry deLaPorte DelaPorte DelaPorte Harry deLaPorte DelaPorte DelaPorte delaPort deLaPorte deLaPorte deLaPorte delaPort deLaPorte deLaPorte deLaPorte Baker deangelo delaPorte deLaPorte Baker deangelo delaPorte deLaPorte deLaPorte delaPort deLaPorte delaPorte deLaPorte delaPort deLaPorte delaPorte Deangelo delaPort Harry Harry Deangelo delaPort Harry Harry bRown delaPorte smith Smith bRown delaPorte smith Smith delaPort smith Smith smith delaPort smith Smith smith The first column is a list of names in arbitrary order. The sec- ond is an ASCII sort of that list. Third, we have one possible case-insensitive sort of the list. The fourth column is what I really wanted. It is sorted the way these words would be sorted in a dictionary (or lexicon). The third and fourth columns both collect words of identical spelling together, but in the third column, upper and lower case spelling are in arbitrary order, while the fourth column places upper case spelling ahead of lower case spelling. For example, the two occurrences of Smith are widely separated in _____ column 2 because one is capitalized and the other is not. Column 3 brings the two together, but in the wrong order. They might have been in the right order, but the order is strictly arbi- trary. In column 4, Smith comes before smith, and lexicographic _____ _____ sorting will always put them in this order. Notice, also that the two occurrences of delaPort are not together in column 3, but ________ are brought together in column 4. QSORT Text Sorting Utility 12 Lexicographic sorting is achieved by making case-insensitive comparisons of entire keys. If the keys compare equal, an ASCII comparison is made to arbitrate ties. In other words, when "lexicographic" keys in two records have different spelling, the case-insensitive comparison determines the order of the records. When "lexicographic" keys are spelled the same, the case- sensitive comparison determines the order of the records. Lexicographic keys are defined, as indicated above, by placing the letter 'L' immediately following the slant-bar (/) in 'L' (/) <key_spec> definitions. __________ Lexicographic sorting can be very useful when needed, but be aware that unnecessarily specifying lexicographic ordering may degrade performance of QSORT. Examples Examples Produce a sorted directory listing and display it on the console a screen's worth at a time: A>DIR | QSORT | MORE A>DIR | QSORT | MORE This demonstrates the use of QSORT as a "filter" in a "pipe." Produce a directory listing sorted by creation date and time, and display it on the console a screen's worth at a time: A>DIR | QSORT /30:2 /24:5 /39 /34:5 | MORE A>DIR | QSORT /30:2 /24:5 /39 /34:5 | MORE The output of the DIR command is piped to QSORT. The keys de- fined are, from left to right (major to minor), year (2 digits), month and day, AM/PM flag and time. The output of QSORT is then piped to MORE for display. Next, replace the unsorted FILE.TXT with the same data sorted in reverse order. Use columns 10 to 16 as the sort key: C> QSORT FILE.TXT /-10:7 C> QSORT FILE.TXT /-10:7 or or C> QSORT FILE.TXT /10:7 /R C> QSORT FILE.TXT /10:7 /R or or C> QSORT FILE.TXT /R /+10 C> QSORT FILE.TXT /R /+10 QSORT Text Sorting Utility 13 Next, perform a simple sort on a file with up to 240-byte records: C> QSORT LARGE.REC /M240 C> QSORT LARGE.REC /M240 or or C> QSORT LARGE.REC C> QSORT LARGE.REC Note that the "/M240" parameter is no longer needed, but will " " not hurt. GLOSS.TXT is an unsorted glossary of terms. The term being de- fined by each entry appears first, followed by several lines of definition. The entries are separated by empty lines. Produce GLOSS.SRT, a sorted version of the glossary: with redirection with redirection C> QSORT /T <GLOSS.TXT >GLOSS.SRT C> QSORT /T <GLOSS.TXT >GLOSS.SRT or without redirection or without redirection C> QSORT /T GLOSS.TXT GLOSS.SRT C> QSORT /T GLOSS.TXT GLOSS.SRT A lawyer keeps a running log of his billable activities in TIME.LOG. The first line of each entry is "mm/dd/yy hh:mm ac- count#." He always places a tilde (~) in the last line of each entry. He wishes to sort the log by account number, and by as- cending date and time within each account: C> QSORT /16:7 /7:2 /1:5 /10:5 /T~ TIME.LOG C> QSORT /16:7 /7:2 /1:5 /10:5 /T~ TIME.LOG The directory of users for a bulletin board system is kept in a binary file of fixed-length records 180 bytes long. The user name is a 26-character field beginning in the first position and the city/state field is a 16-character field beginning in the fortieth position. Sort the file by city/state and name. C> QSORT /F180 /40:16 /1:26 USER.BBS C> QSORT /F180 /40:16 /1:26 USER.BBS QSORT Text Sorting Utility 14 DB.TXT is a delimited field output file from dBASE III. Each record contains 7 fields, delimited by commas. Sort the file to the screen using field 3 as a sort key. C> QSORT /D7 /3. <DB.TXT C> QSORT /D7 /3. <DB.TXT Here, "standard input" has been redirected to the file. Since no redirection is given for "standard output," DOS assigns it to the console by default. This is not a "sort-in-place!" ___ You have received a member list from the Society of End-users of XENIX (SEX.LST). Sort the list by special interest (10 columns beginning at 70) and name (30 columns beginning at 1). Note that the file contains no carriage return characters. Since SEX.LST is a very large file, we wish to obtain running status reports and a final statistics report. C> QSORT SEX.LST /70:10 /1:30 /D,\L /SV C> QSORT SEX.LST /70:10 /1:30 /D,\L /SV The /D parameter is used to redefine the newline sequence as a /D naked line feed character. The file LABEL.TXT contains mailing label images. Each label is 6 lines (1 inch) high. Line six is always empty and line three is frequently empty. An extended Zip code always begins in col- umn 20 of line 5, and extends to the end of the line. In order to take advantage of bulk mailing rates, the labels must be sorted into carrier route (CARRT) order. QSORT LABEL.TXT /5.20 /D6\N QSORT LABEL.TXT /5.20 /D6\N We must use a "delimited field" sort rather than a "tagged line" sort for two reasons: 1) Line six is empty, not tagged with a special character. When line three is also empty a label would be broken into two pieces and separated by the sorting process. 2) Our sort key is not at any known offset from the beginning of the label. Its position is fixed only relative to line five. Error Messages and Return Codes Error Messages and Return Codes The QSORT program can encounter a number of different errors dur- ing execution. Each will generate a brief error message on your console. This section will attempt to list the messages you may see, and give you a little more detailed information about what might have caused the problem. QSORT Text Sorting Utility 15 Command Line Errors Command Line Errors The most common causes of error messages are errors in the com- mand line parameters. Particularly when using a complicated set of keys, I recommend the use of "/?" as the last parameter. If "/?" QSORT discovers an error, it will be reported. The QSORT program will also show you exactly what it would have done, had the "/?" "/?" parameter not been there, but will not perform a sort. ___ You may then hit the "F3" key to recall the command, edit any bad "F3" parameters using the left and right cursor keys and the "INS" and "DEL" keys. When the command parses without error, and the re- port looks like the kind of sort you wish to make, hit the "F3" "F3" key once more, then back space over the "/?" parameter, then hit "/?" "Enter" and QSORT will do the rest. One or more of the following errors might be encountered in the command line: Three file names specified Three file names specified At most, only two file names may be given, an input file and an output file. The most likely cause of this message is forgetting to use the "/" character at the beginning of a key spec or other "/" parameter. Invalid command line parameter "<parameter>" Invalid command line parameter "<parameter>" ___________ This message is issued if QSORT receives a parameter it does not understand. It is usually a typographic error. You meant "/D" "/D" and hit "/E" by mistake. The message displays the actual "/E" <parameter> it did not understand. ___________ /D, /F and /T parameters are incompatible /D, /F and /T parameters are incompatible Each of the above parameters tells QSORT to use a different scan- ning routine to parse records. Since only one such routine can be used, it is an error to use more than one of these parameters. In those unusual situations where more than one might apply, use the most efficient one. (The order of the parameters in this message is from most efficient to least efficient. See the sec- tion on "Performance and Input Record Type" for more informa- tion.) Multiple /<parameter> parameters encountered Multiple /<parameter> parameters encountered ___________ This message again applies to the /D, /F and /T parameters. In /D /F /T this case, the same parameter appears twice in the command line. /F<length> parameter with invalid <length> /F<length> parameter with invalid <length> No substitution is made for "<length>" in this message. This is "<length>" the actual message displayed. It means that either there was no length specified, or the specified length was zero. QSORT Text Sorting Utility 16 Keyfield "<key_spec>" begins beyond end of record Keyfield "<key_spec>" begins beyond end of record __________ Keyfield "<key_spec>" extends beyond end of record Keyfield "<key_spec>" extends beyond end of record __________ These two messages refer to fixed-length records. A key specifi- cation has told QSORT that data exists beyond the bounds of the record. For instance, suppose that /F20 has been specified. /F20 Then /23 would invoke the first message because the record is /23 only 20 characters long. Similarly /18:5 begins before the end /18:5 of the record but extends beyond it, and would invoke the second message. Note that /18 is OK. QSORT will assume a length of /18 three in this case. Invalid delimited field specification - "<key_spec>" Invalid delimited field specification - "<key_spec>" __________ This one is similar to the previous messages. The "field number" portion of a key specification was greater than the defined num- ber of fields. For example "/D5 /6.1:3" would provoke QSORT into "/D5 /6.1:3" issuing this message. It's hard to find field 6 in a 5-field record. Multiple STDERR redirections Multiple STDERR redirections At most, the standard error output may be redirected once. A second attempt to do so will fail with this message. Invalid STDERR redirection Invalid STDERR redirection Two conditions cause this message; use of 2> or 2>> as the last 2> 2>> parameter, with no file specified, or use of 2>&<x> where <x> is 2>& ___ ___ any text other than an unadorned hyphen. ABORT -- Error(s) in command line parameter(s) ABORT -- Error(s) in command line parameter(s) If any of the above messages are issued, QSORT will continue to scan the command line and evaluate the parameters, but will even- tually issue this message too. If there are command line errors, QSORT will not guess about your data. It will stop! ___ Memory Errors Memory Errors ABORT -- Buffer allocation error ABORT -- Buffer allocation error An error of unknown origin occurred when QSORT was trying to al- locate memory for its buffers. The most likely cause here is a "memory poor" condition caused by a too small partition under a multitasker such as DoubleDOS, or perhaps too many "terminate- and-stay-resident" programs. As an absolute minimum, QSORT must be able to obtain eight kilobytes of contiguous memory for its sort buffer. QSORT Text Sorting Utility 17 ABORT -- Insufficient memory ABORT -- Insufficient memory This one can occur at any time during the sort. QSORT must have a sort buffer large enough to hold the two largest records in the file. Typically, the sort buffer is about fifty kilobytes, which means that if records are shorter than about twenty five kilo- bytes, QSORT can usually handle them. This is normally a problem only when using the /T parameter. /T I/O Errors I/O Errors ABORT -- Unable to open "<file_spec>" for input ABORT -- Unable to open "<file_spec>" for input ___________ QSORT was attempting to open <file_spec> for input. If ___________ <file_spec> is your input file, you probably misspelled the name. ___________ If <file_spec> has the form "number.SRT" QSORT could not find a ___________ merge file it thought it had created. If this happens you may have discovered a bug. Please send me full particulars ASAP! ABORT -- Unable to open "<file_spec>" for output ABORT -- Unable to open "<file_spec>" for output ___________ QSORT was attempting to open <file_spec> for output, and the open ___________ operation failed. The most likely cause is that you ran out of disk space, and DOS was unable to expand a subdirectory. A root directory cannot be expanded, and you may have run out of direc- tory space. DOS will also complain if you attempt to open a file with the same full name as an existing subdirectory. ABORT -- Error reading input or merge file ABORT -- Error reading input or merge file The section of the program which issues this message does not know the file name, so cannot help you much there. This message may mean that your disk has a sector going bad. (Well, it can't all be good news!) ABORT -- Error writing to merge or output file ABORT -- Error writing to merge or output file This one could also mean a bad sector, but a far more likely cause is that you just ran out of disk space. Internal Errors Internal Errors ABORT -- Internal QSORT error ABORT -- Internal QSORT error In theory, this is an error which "can't happen." If you EVER _______________ get this message, please notify me with as many details as you can supply. Actually I have NEVER seen this message issued by a released version of QSORT. QSORT Text Sorting Utility 18 ERRORLEVEL Return Codes ERRORLEVEL Return Codes When QSORT successfully completes a sort, it terminates with DOS ERRORLEVEL set to zero. (See your DOS manual for more information on ERRORLEVEL.) If it terminates for ANY other reason, it sets ERRORLEVEL to a non-zero value, which can be tested in a batch file. The following are the ERRORLEVEL codes QSORT uses, and their meanings: Code Meaning 0 Successful completion 1 Command line error and/or "/?" parameter specified "/?" 2 Open-for-read error 3 Open-for-write error 4 I/O error reading file 5 I/O error writing file 6 Memory error 255 Internal error Implementation Notes Implementation Notes General Information General Information QSORT is intended as an enhanced replacement for DOS SORT. It is nearly fully upward compatible, but provides much more flexi- bility. Multiple sort keys may be specified, a pseudo in-place sort may be performed and files and/or records of any size may be sorted provided only that there is sufficient disk space for work files and the output file. QSORT uses the "quick sort" algo- rithm, which cannot guarantee the order of records whose keys are all equal. This is the one "incompatibility" with DOS SORT, which retains the original order of records when its only key compares equal. This is important to SORT because it must be in- voked multiple times to effect a multiple key sort. With QSORT, you only sort once and there are usually enough keys available to insure you get the order you want the first time. QSORT uses a sort buffer of about 50K bytes and will fill the buffer as full as possible, and then sort its contents. If the end of the input file has been reached and no temporary work files have been generated, the sorted contents of the buffer are written to the output file, completing the sort operation. If the input file is too large to fit into the sort buffer, as much of the input file as possible is read into the buffer, sorted, then written to a temporary work file. This process is repeated as many times as necessary to process the entire input file, each time creating a new work file for the sorted output. QSORT Text Sorting Utility 19 Upon completion of the "sort phase," QSORT begins a "merge phase." Each work file is a sorted sub-set of the input file. Thus, work files may be read sequentially and combined to produce a sorted output. QSORT will open as many work files as DOS per- mits (more on this later). If all the remaining work files can be opened, the sorted result is written to the output file. Otherwise, a new work file is created and another merge pass will be required. On each merge pass, the number of work files is re- duced and eventually all remaining work files will be opened and the sorted output file will be written completing the sort oper- ation. Performance and DOS Configuration Performance and DOS Configuration QSORT is smart enough to never have just one work file remaining, which would require an unnecessary copy operation. In fact, QSORT is smarter than just that in its handling of the merge phase. If more than one merge pass is required, all the data merged during the first pass will have to be merged again, so QSORT attempts to minimize the first pass. For example, if QSORT discovers it may only open 15 files at a time, and there are 16 temporary files, it will only merge two files on the first pass, creating a 17th file as it does. Then in the second pass, it will merge all 15 remaining files to the output file. The less data it processes twice, the faster it performs the sort! With nothing else to guide it, QSORT places its temporary files in the default directory. Either of two "environment variables" can override this. (See your DOS manual for information on envi- ronment variables and the SET command.) The DOS command: SET QSTMP=<path> or SET QSTMP=<path> or ______ SET TMP=<path> or SET TMP=<path> or ______ SET TEMP=<path> SET TEMP=<path> ______ will define a path for QSORT to use for its temporaries. QSORT first looks for the environment variable QSTMP. If it does not exist, QSORT next looks for TMP or TEMP in that order. TMP and TEMP are de facto standards used by many programs, and are usu- ally defined in your AUTOEXEC.BAT batch file. You might have TMP specifying a 64K RAM disk to speed up your compiler. In this case, an attempt to sort a 100K file is doomed to failure. Rather than redefine TMP, you may define QSTMP to force QSORT to use some directory on your hard disk. In fact: SET QSTMP=\ SET QSTMP=\ tells QSORT to always use the root directory of the default drive! QSORT Text Sorting Utility 20 CAUTION! The root directory has a fixed size, and is CAUTION! The root directory has a fixed size, and is NOT expandable. For a hard disk, it typically has room NOT expandable. For a hard disk, it typically has room for only 512 file names, less one for each subdirectory for only 512 file names, less one for each subdirectory and one for the volume label (if any). Large files may and one for the volume label (if any). Large files may fail to sort if the QSORT program must place too many fail to sort if the QSORT program must place too many merge files in a root directory. Subdirectories, on merge files in a root directory. Subdirectories, on the other hand, are limited only by available disk the other hand, are limited only by available disk space. space. QSORT, to work properly, needs enough space on the output disk to hold the output file. Even if the input file is to be deleted and resides in the same directory, that is not done until after the output file has been successfully written. If one merge pass is required, the disk space QSORT uses for temporary merge files will be about 10% larger than the size of the input file. If more than one merge pass will be required, allow about twice the size of the input file as temporary merge file space. One of the advantages of controlling where QSORT places its tem- porary files is to insure adequate space for them. A second is speed. If the temporary files can be placed on a separate disk from the input and output files, disk seeking is minimized and performance improved. Each time QSORT must create a new temporary merge file, the data put into it will be processed again. Obviously, the more files QSORT can open during the merge phase, the fewer times it will have to handle each record and the faster it can sort large files. If DOS is properly pre-conditioned, QSORT can have up to 15 temporary merge files open at once, and very large files can be sorted with just one sort pass and one merge pass. Unfortu- nately, that capability is not automatic. DOS has a fixed number of file "handles" that it associates with open files. The default number is eight, but DOS opens five of them for standard input, standard output, standard error, stan- dard printer and standard auxiliary device. That leaves three for merging. A 250K input file would produce five temporary merge files and that would take three merge passes; merge two into one, leaving four; merge two into one leaving three; and fi- nally merge three into the output file. In the process, QSORT must read and write about 80% of the file twice during the merge phase. Worse yet, since you need at least three handles for merging, if you have resident programs that have open files, you can't merge at all! DOS can be told to set aside more space for file handles. Each handle is only 39 bytes and it's memory very well spent. One process can have a maximum of 20 handles open at one time, but since resident processes may be using handles, I recommend 25 to 35. To do this, the root directory of the disk or disks you boot ______________________ from must contain a file named CONFIG.SYS. If your boot disk(s) ____ QSORT Text Sorting Utility 21 already contains a CONFIG.SYS, edit it, or if not, create it to contain the following line: FILES=25 (or more) FILES=25 (or more) While we're at it, let's add one more thing to CONFIG.SYS which will improve the performance of QSORT and many other programs as well. DOS provides, by default, two disk buffers. These are the buffers it uses to do its disk reads and writes. During the merge phase QSORT may have many files open at once, reading from them in more or less random order. DOS may have to read the same physical sector several times to get all its data. But DOS can remember what's in each buffer and where it came from, and will not re-read a sector it already has in a buffer. DOS needs 528 bytes for each buffer. I recommend 20 buffers to make QSORT per- form well under the most adverse conditions. This will require an additional 9504 bytes or slightly more than 9K, again memory well spent, so we add to CONFIG.SYS the following line: BUFFERS=20 BUFFERS=20 See your DOS manual for more information on CONFIG.SYS. Performance and Input Record Type Performance and Input Record Type QSORT must read and parse logical records before sorting them, then reassemble them before final output. The type of records contained in the file being sorted determines how much work this requires, and therefore has an impact on performance. The present version of QSORT can handle four record types: simple ASCII, tagged ASCII, delimited field ASCII and fixed length, de- termined by the presence or absence of a /T, /D or /F parameter /T /D /F on the command line. Fixed length records are very structured and require no parsing. Other things equal, files of fixed length records will sort the fastest. When parsing simple ASCII records, QSORT must find and mark the newline sequence, then restore it for final output. In general, this is relatively fast, but is affected by line length. In par- ticular, lines containing "over-strikes" (naked CR characters followed by more data) can significantly slow down the parsing. Tagged ASCII records are parsed in a fashion similar to simple ASCII records, if a tag character is defined. First the tag character is found, then the next newline sequence is found and marked. The time required is of course dependent on the total length of the logical record, but is fairly fast. If no tag character is defined, two successive newline sequences must be found. This depends not only on total length, but the number of lines contained in a logical record. QSORT Text Sorting Utility 22 To parse a delimited field record with n fields, n minus one de- __ __ limiters must be found and marked, then the newline sequence must be found and marked. It is similar to tagged records with no de- fined tag character, but because records of this type are usually shorter than tagged records, parsing delimited field records may be a little faster. It is certainly slower than parsing simple ASCII records. Performance and Sort Keys Performance and Sort Keys The sort keys defined on the command line have a lot to do with QSORT's performance. There isn't much you can do by way of a strategy, when you need a particular file sorted in a particular way, but you should at least be aware. Several decisions must be made in comparing two records. Which field contains the current key? Is the field long enough to con- tain the key in one, both or neither record? Are the keys lexicographic or ASCII? If the answers to any of these questions will remain constant over the course of a sort run, they should be answered once, not several thousand times! QSORT has ten record comparison routines varying in degree of complexity. At the beginning of each sort run it selects the simplest one possible, based on the parameters given, to be used throughout the run. If no sort key parameters are given, the entire record is used as a key. The compare routine has no decisions it must make -- it simply compares the two strings handed it. This is the "simple sort," and is the fastest possible case. A sort key that does not begin at the beginning of a variable length record, may not be contained in a particular record at all, while a fixed length record is known to contain all keys. Other things equal, files of fixed length records will sort some- what faster because the compare routine does not have to test for "key containment." Lexicographic keys are first compared with a "case insensitive" technique. Each character is tested to see if it is alphabetic. If it is, it is converted to lower case. Then the converted character from each record is compared. This is obviously slower than directly comparing two characters. In the event lexicographic keys compare equal, they are compared a second time using a direct compare technique! Files with lexicographic keys sort slower than similar files without them. In the case of files with delimited field records, the compare routine must find the correct field for each key, determine if the keys are contained within the fields, and finally compare them. The added step of searching for fields slows record com- parison. QSORT Text Sorting Utility 23 In general, the more complex the data, the more complex the sort- ing task and the longer it will take. QSORT attempts to optimize its performance by making as many decisions as it can about your data up front, then selecting a compare routine that makes only the necessary decisions on a record-by-record basis. Performance and File Size Performance and File Size I received a letter from someone which included a graph showing QSORT's performance in sorting time vs. file size. He said he had expected an exponential, or at least a logarithmic curve. Instead time increased linearly with file size. I admit, it puz- zled me at the time, but Codeview, Microsoft's debugger, made it ease for me to measure the performance of the various parts of the QSORT program. It turns out that actual sorting of data ac- counts for a very small percentage of QSORT's running time. It spends most of its time doing I/O. For files up to about 50 kilobytes, it will read and write each record once. From 50K to about 750K there will be one merge pass and each record will be read and written twice. Since the amount of I/O increases lin- early over this range of file sizes, so will sorting time. Above about 750K a second merge pass will be needed, but in this size range, only seven to ten percent of the data will be pro- cessed in the first merge pass, so the sort time vs size curve will steepen slightly, but will not experience a large step (as it did in versions 1 and 2). Doubling the file size to 1.5 megabytes should increase the sort time about three times. Sorting time will be approximately proportional to file size times the "average passes over data" number from the statistics report. Since this number remains a constant "2.0" over a wide range of file sizes, sorting time will be a linear function of file size in that range. I hope you find this program useful. Your comments and sugges- tions are welcome.