IRIX Base Documentation 2001 May

home *** CD-ROM | disk | FTP | other *** search

/ IRIX Base Documentation 2001 May / SGI IRIX Base Documentation 2001 May.iso / usr / share / catman / u_man / cat1 / at.z / at

Wrap

Text File | 2001-04-17 | 25.0 KB | 661 lines

aaaatttt((((1111)))) aaaatttt((((1111)))) NNNNAAAAMMMMEEEE at, batch - execute commands at a later time SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS aaaatttt [-m] [-f _f_i_l_e] [-q _q_u_e_u_e_n_a_m_e] -t _t_i_m_e aaaatttt [-m] [-f _f_i_l_e] [-q _q_u_e_u_e_n_a_m_e] _t_i_m_e_s_p_e_c aaaatttt ----rrrr _a_t__j_o_b__i_d ... aaaatttt ----llll ----qqqq _q_u_e_u_e_n_a_m_e aaaatttt ----llll [_a_t__j_o_b__i_d ...] bbbbaaaattttcccchhhh DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN _a_t and _b_a_t_c_h read commands from standard input to be executed at a later time. _a_t allows you to specify when the commands should be executed, while jobs queued with _b_a_t_c_h will execute when system load level permits. The _a_t utility reads commands from standard input and groups them together as an _a_t-_j_o_b, to be executed at a later time. The at-job will be executed in a separate invocation of the shell, running in a separate process group with no controlling terminal, except that of the environment variables, current working directory, file creation mask, and other implementation-dependent execution-line attributes in effect when the _a_t utility is executed wil be retained and used when the at-job is executed. The shell umask and ulimit are retained when the commands are executed. Open file descriptors, traps, and priority are lost. When the at-job is submitted, the _a_t__j_o_b__i_d and scheduled time are written to standard error. The _a_t__j_o_b__i_d is an identifier that will be a string consisting solely of alphanumeric characters and the period character. The _a_t__j_o_b__i_d is assigned by the system when the job is scheduled such that it uniquely identifies a particular job. User notification and the processing of the job's standard output and standard error are described under the ----mmmm option. If the file ////uuuussssrrrr////lllliiiibbbb////ccccrrrroooonnnn////aaaatttt....aaaalllllllloooowwww. exists, only users whose names appear in the file are permitted to use _a_t. This restriction applies to all users, including root. If that file does not exist, the file ////uuuussssrrrr////lllliiiibbbb////ccccrrrroooonnnn////aaaatttt....ddddeeeennnnyyyy is checked to determine if the user should be denied access to _a_t. If neither file exists, only a process with the appropriate privileges is allowed to submit a job. If only aaaatttt....ddddeeeennnnyyyy exists and is empty, global usage is permitted. The aaaatttt....aaaalllllllloooowwww and aaaatttt....ddddeeeennnnyyyy files consist of one user name per line. These files can only be modified by the superuser. OOOOPPPPTTTTIIIIOOOONNNNSSSS The _a_t utility supports the XXXXBBBBDDDD specification, SSSSeeeeccccttttiiiioooonnnn 11110000....2222,,,, UUUUttttiiiilllliiiittttyyyy SSSSyyyynnnnttttaaaaxxxx GGGGuuuuiiiiddddeeeelllliiiinnnneeeessss. PPPPaaaaggggeeee 1111 aaaatttt((((1111)))) aaaatttt((((1111)))) _a_t may be used with the following options: ----ffff ffffiiiilllleeee Specify the pathname of a file to be used as the source of the at- job, instead of standard input. ----llll (The letter ell.) Report all jobs scheduled for the invoking user if no _a_t__j_o_b__i_d operands are specified. If _a_t__j_o_b__i_d_s are specified, report only information on these jobs. The output will be written to standard output. ----mmmm Send mail to the invoking user after the at-job has run, announcing its completion. Standard output and standard error produced by the at-job will be mailed to the user as well, unless directed elsewhere. Mail will be sent even if the job produces no output. If ----mmmm is not used, the job's standard output and standard error will be provided to the user by means of mail, unless they are redirected elsewhere; if there is no such output to provide, the implementation needs not notify the user of the job's completion. ----qqqq qqqquuuueeeeuuuueeeennnnaaaammmmeeee Specify in which queue to schedule a job for submission. When used with the ----llll option, limit the search to that particular queue. By default, at-jobs will be scheduled in queue aaaa. In contrast, queue bbbb is reserved for batch jobs. (see the _b_a_t_c_h utility.) The meanings of all other _q_u_e_u_e_n_a_m_e_s are implementation-dependent. ----rrrr Remove the jobs with the specified _a_t__j_o_b__i_d_s that were previously scheduled with _a_t. You can only remove your own jobs unless you are the superuser. ----tttt ttttiiiimmmmeeee Submit the job to be run at the time specified by the _t_i_m_e option argument, which must have the format as specified by the _t_o_u_c_h utility. All jobs are placed on a specific queue. By default, _a_t jobs go on queue ``a'', _b_a_t_c_h jobs go on queue ``b''. Additional queues may be created by altering the ////uuuussssrrrr////lllliiiibbbb////ccccrrrroooonnnn////qqqquuuueeeeuuuueeeeddddeeeeffffssss file. _q_u_e_u_e_d_e_f_s(4) defines the format for that file. Note that queue names must be lower case letters. OOOOPPPPEEEERRRRAAAANNNNDDDDSSSS The following operands are supported: _a_t__j_o_b__i_d The name reported by a previous invocation of the _a_t utility at the time the job was scheduled. _t_i_m_e_s_p_e_c Submit the job to be run at the date and time specified. All of the _t_i_m_e_s_p_e_c operands are interpreted as if they were separated by space PPPPaaaaggggeeee 2222 aaaatttt((((1111)))) aaaatttt((((1111)))) characters and concatenated, and are parsed as described in the grammar at the end of this section. The date and time are interpreted as being the timezone of the user (as determined by the _T_Z variable), unless a timezone name appears as part of _t_i_m_e below. In the POSIX locale, the following describes the three parts of the time specification string. All of the values from the LC_TIME categories in the POSIX locale are recognized in a case-insensitive manner. _t_i_m_e The _t_i_m_e can be specified as one, two, or four digits. One- and two-digit numbers are taken to be hours, four-digit numbers to be hours and minutes. The time can alternatively be specified as two numbers separated by a colon, meaning _h_o_u_r:_m_i_n_u_t_e. An AM/PM indication (one of the values from the am_pm keywords in the LC_TIME locale category) can follow the time; otherwise, a 24-hour clock time is understood. A timezone name can also follow to further qualify the time. The acceptable timezone names are implementation-dependent, except that they will be case-insensitive and the string utc is supported to indicate the time in Coordinated Universal Time. The suffix zzzzuuuulllluuuu may be used to indicate GMT. The _t_i_m_e field can also be one of the following tokens in the POSIX locale: mmmmiiiiddddnnnniiiigggghhhhtttt Indicates the time 12:00 am (00:00). nnnnoooooooonnnn Indicates the time 12:00 pm. nnnnoooowwww Indicates the current day and time. Invoking _a_t _n_o_w will submit an at-job for potentially immediate execution (that is, subject only to unspecified scheduling delays). _d_a_t_e An optional _d_a_t_e can be specified as either a month name (one of the values from the mmmmoooonnnn or aaaabbbbmmmmoooonnnn keywords in the LC_TIME locale category) followed by a day number (and possibly year number preceded by a comma, two digit years 00-37 and 70-99 represent 2000-2037 and 1970-1999 respectively, all years inclusive) or a day of the week (one of the values from the ddddaaaayyyy or aaaabbbbddddaaaayyyy keywords in the LC_TIME locale category). Two special days are recognized in the POSIX locale: ttttooooddddaaaayyyy Indicates the current day. ttttoooommmmoooorrrrrrrroooowwww Indicates the day following the current day. PPPPaaaaggggeeee 3333 aaaatttt((((1111)))) aaaatttt((((1111)))) If no _d_a_t_e is given, ttttooooddddaaaayyyy is assumed if the given hour is greater than the current hour and ttttoooommmmoooorrrrrrrroooowwww is assumed if it is less. If the given month is less than the current month (and no year is given), next year is assumed. _i_n_c_r_e_m_e_n_t The optional _i_n_c_r_e_m_e_n_t is simply a number preceded by a plus sign (+) and suffixed by one of the following: mmmmiiiinnnnuuuutttteeeessss, hhhhoooouuuurrrrssss, ddddaaaayyyyssss, wwwweeeeeeeekkkkssss, mmmmoooonnnntttthhhhssss, or yyyyeeeeaaaarrrrssss. (The singular form is also accepted.) The keyword next is equivalent to an increment number of +1. For example, the following are equivalent command: at 2pm + 1 week at 2pm next week Thus legitimate commands include: at 0815am Jan 24 at 8:15am Jan 24 at now + 1 day at 5 pm Friday The following grammar describes the precise format of _t_i_m_e_s_p_e_c in the POSIX locale. This formal syntax takes precedence over the preceding text syntax description. When used in a _t_i_m_e_s_p_e_c, white space also delimits tokens. %token hr24clock_hr_min %token hr24clock_hour /* A hr24clock_hr_min is a one, two or four digit number. A one or two digit number constitutes a hr24clock_hour. A hr24clock_hour may be any of the single digits '0' - '9', or may be double digits, ranging from "00" - "23". If a hr24clock_hr_min is a four digit number, the first two digits must be valid hr24clock_hour, while the last two represent the number of minutes, from "00" - "59". */ %token wallclock_hr_min %token wallclock_hour /* A wallclock_hr_min is a one, two or four digit number. A one or two digit number constitutes a wallclock_hour. A wallclock_hour may be any of the single digits '1' - '9', or may be double digits, ranging from "01" - "12". If a wallclock_hr_min is a four digit number, the first two digits must be valid wallclock_hour, while the last two represent the number of minutes, from "00" - "59". */ %token minute /* PPPPaaaaggggeeee 4444 aaaatttt((((1111)))) aaaatttt((((1111)))) A minute is a one or two digit number whose values can be '0' - '9' or "00" - "59". */ %token day_number /* A day_number is a number in the range appropriate for the particular month and year specified by month_name and year_number, respectively. If no year_number is given, the current year is assumed if the given date and time are later this year. If no year_number is given and the date and time have already occurred this year and the month is not the current month, next year is the assumed year. */ %token year_number /* A year_number is a four digit number representing the year A.D., in which the at_job is to be run */ %token inc_number /* The inc_number is the number of times the succeeding increment period is to be added to the specified date and time. */ %token timezone_name /* The name of an optional timezone suffix to the time field, in an implementation dependent format. */ %token month_name /* One of the values from the "mon" or "abmon" keywords in the LC_TIME locale category. */ %token day_of_week /* One of the values from the "day" or "abday" keywords in the LC_TIME locale category. */ %token am_pm /* One of the values from the "am_pm" keyword in the LC_TIME locale category. */ %start timespec %% PPPPaaaaggggeeee 5555 aaaatttt((((1111)))) aaaatttt((((1111)))) timespec : time | time date | time increment | time date increment | nowspec ; nowspec : "now" | "now" increment ; time : hr24clock_hr_min | hr24clock_hr_min timezone_name | hr24clock_hour ":" minute | hr24clock_hour ":" minute timezone_name | wallclock_hr_min am_pm | wallclock_hr_min am_pm timezone_name | wallclock_hour ":" minute am_pm | wallclock_hour ":" minute am_pm timezone_name | "noon" | "midnight" ; date : month_name day_number | month_name day_number "," year_number | day_of_week | "today" | "tomorrow" ; increment : "+" inc_number inc_period | "next" inc_period ; inc_period : "minute" | "minutes" | "hour" | "hours" | "day" | "days" | "week" | "weeks" | "month" | "months" | "year" | "years" ; _b_a_t_c_h submits a batch job. It is almost equivalent to _a_t _n_o_w, but not quite. For one, it goes into a different queue. SSSSTTTTDDDDIIIINNNN The standard input must be a text file consisting of commands acceptable to the shell command language. The standard input will only be used if no -_f _f_i_l_e option is specified. PPPPaaaaggggeeee 6666 aaaatttt((((1111)))) aaaatttt((((1111)))) EEEENNNNVVVVIIIIRRRROOOONNNNMMMMEEEENNNNTTTT VVVVAAAARRRRIIIIAAAABBBBLLLLEEEESSSS The following environment variables affect the execution of _aaaa_tttt: _LLLL_AAAA_NNNN_GGGG provide a default value for the internationalization variables that are unset or null. If _L_A_N_G is unset or null the corresponding value from the implementation-specific default locale will be used. If any of the internationalization variables contains an invalid setting, the utility will behave as if none of the variables had been defined. _LLLL_CCCC______AAAA_LLLL_LLLL if set to a non-empty string value, override the values of all the other internationalization variables. _LLLL_CCCC______CCCC_TTTT_YYYY_PPPP_EEEE determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single - as opposed to multi- byte - characters in arguments). _LLLL_CCCC______MMMM_EEEE_SSSS_SSSS_AAAA_GGGG_EEEE_SSSS determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error. _NNNN_LLLL_SSSS_PPPP_AAAA_TTTT_HHHH determine the location of message catalogs for the processing of _LLLL_CCCC______MMMM_EEEE_SSSS_SSSS_AAAA_GGGG_EEEE_SSSS. _LLLL_CCCC______TTTT_IIII_MMMM_EEEE determine the format and contents of date and time strings written by _a_t _SSSS_HHHH_EEEE_LLLL_LLLL determine a name of a command interpreter to be used to invoke the at-job. If the variable is unset or null, _s_h will be used. If it is set to a value other than a name for _s_h, the implementation will do one of the following: use that shell; use _s_h; use the login shell from the user database; or any of the preceding accompanied by a warning diagnostic about which was chosen. _TTTT_ZZZZ determine the time zone. The job will be subnmitted for execution at the time specified by _t_i_m_e_s_p_e_c or ----tttt _t_i_m_e relative to the timezone specified by the TZ variable. If _t_i_m_e_s_p_e_c specifies a timezone, it will override _T_Z. If _t_i_m_e_s_p_e_c does not specify a timezone and _T_Z is unset or null, an unspecified default timezone will be used. SSSSTTTTDDDDOOOOUUUUTTTT When standard input is a terminal, prompts of unspecified format for each line of the user input described in SSSSTTTTDDDDIIIINNNN may be written to standard output. PPPPaaaaggggeeee 7777 aaaatttt((((1111)))) aaaatttt((((1111)))) In the POSIX locale, the following will be written to the standard output for each job when jobs are listed in response to the ----llll option: "%s\t%s\n", _a_t__j_o_b__i_d, <_d_a_t_e> where <_d_a_t_e> is equivalent in format to the output of: date +"%a %b %e %T %Y" The date and time written will be adjusted so that they appear in the timezone of the user (as determined by the _T_Z variable). SSSSTTTTDDDDEEEERRRRRRRR The following will be written to standard error when a job has been successfully submitted: "job %s at %s\n", _a_t__j_o_b__i_d, <_d_a_t_e> where <_d_a_t_e> has the same format as is described in SSSSTTTTDDDDOOOOUUUUTTTT interpreter, are considered a diagnostic that changes the exit status. Diagnostic messages, if any, are written to standard error. EEEEXXXXIIIITTTT SSSSTTTTAAAATTTTUUUUSSSS The following exit values are returned: _0000 successful completion _>>>>_0000 an error occurred CCCCOOOONNNNSSSSEEEEQQQQUUUUEEEENNNNCCCCEEEESSSS OOOOFFFF EEEERRRRRRRROOOORRRRSSSS The job will not be scheduled, removed or listed. EEEEXXXXAAAAMMMMPPPPLLLLEEEESSSS The _a_t and _b_a_t_c_h commands read from standard input the commands to be executed at a later time. 1. This sequence can be used at a terminal: at -m 0730 tomorrow sort <file >outfile EOT 2. This sequence, which demonstrates redirecting standard error to a pipe, is useful in a command procedure (the sequence of output redirection specifications is significant): at now + 1 hour <<! diff file1 file2 2>&1 >outfile | mailx mygroup PPPPaaaaggggeeee 8888 aaaatttt((((1111)))) aaaatttt((((1111)))) 3. To have a job reschedule itself, _a_t can be invoked from within the at-job. For example, this daily processing script named mmmmyyyy....ddddaaaaiiiillllyyyy will run every day (although _c_r_o_n_t_a_b is a more appropriate vehicle for such work): #my.daily runs every day _d_a_i_l_y _p_r_o_c_e_s_s_i_n_g at now tomorrow < my.daily 4. The spacing of the three portions of the POSIX locale _t_i_m_e_s_p_e_c is quite flexible as long as there are no ambiguities. Examples of various times and operand presentation include: at 0815am Jan 24 at 8 :15amjan24 at now "+ 1 day" at 5 pm FRIday _s_h(1) provides different ways of specifying standard input. Within your commands, it may be useful to redirect standard output. 5. This sequence can be used at a terminal: batch sort _f_i_l_e_n_a_m_e >_o_u_t_f_i_l_e <control-D> (hold down 'control' and depress 'D') 6. This sequence, which demonstrates redirecting standard error to a pipe, is useful in a shell procedure (the sequence of output redirection specifications is significant): batch <<! sort _f_i_l_e_n_a_m_e 2>&1 >_o_u_t_f_i_l_e | mail _l_o_g_i_n_i_d ! 7. To have a job reschedule itself, invoke _a_t from within the shell procedure, by including code similar to the following within the shell file: echo "sh _s_h_e_l_l_f_i_l_e" | at 1900 thursday next week or, from a terminal at 1900 thursday next week sh _s_h_e_l_l_f_i_l_e <control-D> (hold down 'control' and depress 'D') FFFFIIIILLLLEEEESSSS /usr/lib/cron main cron directory /usr/lib/cron/at.allow list of allowed users /usr/lib/cron/at.deny list of denied users /usr/spool/cron/atjobs spool area /usr/lib/cron/.proto generic prototype, prepended to all jobs /usr/lib/cron/.proto.x prototype for queue `x' /usr/lib/cron/queuedefs definitions for queues PPPPaaaaggggeeee 9999 aaaatttt((((1111)))) aaaatttt((((1111)))) SSSSEEEEEEEE AAAALLLLSSSSOOOO cron(1M), kill(1), mail(1), nice(1), ps(1), sh(1), sort(1), proto(4), queuedefs(4). DDDDIIIIAAAAGGGGNNNNOOOOSSSSTTTTIIIICCCCSSSS Complains about various syntax errors and times out of range. PPPPaaaaggggeeee 11110000