semwait(USP)

Name

semwait : Wait until the specified file exists

Synopsis

Usage   : semwait [option..] <path1> <path2> ..

Options : -a

          -o

          --less_than <n>

          --more_than <n>

          -s <sec>

          -t <time>

          --interval <ms>

Version : Mon Jan 22 09:17:08 JST 2024

Edition : 1

Description

If all specified files (path1 path2 ...) exist, the command exits

normally.  If at least one of the files doesn't exist, the command

waits.  The command checks for the files every one second. You can

use wildcards (* ? []) in path names.

You can specify the deadline timestamp using the -t option in one

of the four formats below:

 HHMM：HourMinute

 HHMMSS：HourMinuteSecond

 YYYYMMDDHHMM：YearMonthDayHourMinute

 YYYYMMDDHHMMSS：YearMonthDayHourMinuteSecond

If the deadline timestamp is passed, the command exits with an error.

You can specify the maximum number of seconds to wait using the -s

option.  When <sec> of seconds has passed since executing the

command, it exits with an error.  You can specify after the decimal

point for <sec> to denote subsecond.

If the --interval option is speified, interval time is changed to

<ms> milliseconds.

The -a options is the default.  It causes the command to wait for

ALL files to exist.

If the -o option is specified, the command exits when any one of

the files exists.

Example 1

Wait until 16:30 for sem1 and sem2 to exist

(An error occurs at 16:30:01)

$ semwait -t 1630 sem1 sem2 || exit 1

Example 2

Wait at most 5 seconds for sem1 and sem2 to exist

$ semwait -s 5 sem1 sem2 || exit 1

Example 3

Change interval time to 100 ms for sem1 and sem2 to exist

$ semwait --interval 100 sem1 sem2

Example 4

Wait until either sem1 or sem2 exists

$ semwait -o sem1 sem2

Example 5

Wait at most 10 seconds for any file starting with 'sem.' to exist

$ semwait -s 10 'sem.*'

Example 6

Wait at most 10 secinds for there to be less than three

files starting with 'sem.'

$ semwait -s 10 --less_than 3 'sem.*'

Example 7

Wait at most 10 secinds for there to be more than three

files starting with 'sem.'

$ semwait -s 10 --more_than 3 'sem.*'