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514.

Evaluate conditional expression.

Exits with a status of 0 (true) or 1 (false) depending on
the evaluation of EXPR. Expressions may be unary or binary. Unary
expressions are often used to examine the status of a file. There
are string operators and numeric comparison operators as well.

The behavior of test depends on the number of arguments. Read the
bash manual page for the complete specification.

File operators:

-a FILE True if file exists.
-b FILE True if file is block special.
-c FILE True if file is character special.
-d FILE True if file is a directory.
-e FILE True if file exists.
-f FILE True if file exists and is a regular file.
-g FILE True if file is set-group-id.
-h FILE True if file is a symbolic link.
-L FILE True if file is a symbolic link.
-k FILE True if file has its `sticky' bit set.
-p FILE True if file is a named pipe.
-r FILE True if file is readable by you.
-s FILE True if file exists and is not empty.
-S FILE True if file is a socket.
-t FD True if FD is opened on a terminal.
-u FILE True if the file is set-user-id.
-w FILE True if the file is writable by you.
-x FILE True if the file is executable by you.
-O FILE True if the file is effectively owned by you.
-G FILE True if the file is effectively owned by your group.
-N FILE True if the file has been modified since it was last read.

FILE1 -nt FILE2 True if file1 is newer than file2 (according to
modification date).

FILE1 -ot FILE2 True if file1 is older than file2.

FILE1 -ef FILE2 True if file1 is a hard link to file2.

String operators:

-z STRING True if string is empty.

-n STRING
STRING True if string is not empty.

STRING1 = STRING2
True if the strings are equal.
STRING1 != STRING2
True if the strings are not equal.
STRING1 < STRING2
True if STRING1 sorts before STRING2 lexicographically.
STRING1 > STRING2
True if STRING1 sorts after STRING2 lexicographically.

Other operators:

-o OPTION True if the shell option OPTION is enabled.
-v VAR[tab] True if the shell variable VAR is set
! EXPR True if expr is false.
EXPR1 -a EXPR2 True if both expr1 AND expr2 are true.
EXPR1 -o EXPR2 True if either expr1 OR expr2 is true.

arg1 OP arg2 Arithmetic tests. OP is one of -eq, -ne,
-lt, -le, -gt, or -ge.

Arithmetic binary operators return true if ARG1 is equal, not-equal,
less-than, less-than-or-equal, greater-than, or greater-than-or-equal
than ARG2.

Exit Status:
Returns success if EXPR evaluates to true; fails if EXPR evaluates to
false or an invalid argument is given.

519.

Modify shell resource limits.

Provides control over the resources available to the shell and processes
it creates, on systems that allow such control.

Options:
-S[tab]use the `soft' resource limit
-H[tab]use the `hard' resource limit
-a[tab]all current limits are reported
-b[tab]the socket buffer size
-c[tab]the maximum size of core files created
-d[tab]the maximum size of a process's data segment
-e[tab]the maximum scheduling priority (`nice')
-f[tab]the maximum size of files written by the shell and its children
-i[tab]the maximum number of pending signals
-l[tab]the maximum size a process may lock into memory
-m[tab]the maximum resident set size
-n[tab]the maximum number of open file descriptors
-p[tab]the pipe buffer size
-q[tab]the maximum number of bytes in POSIX message queues
-r[tab]the maximum real-time scheduling priority
-s[tab]the maximum stack size
-t[tab]the maximum amount of cpu time in seconds
-u[tab]the maximum number of user processes
-v[tab]the size of virtual memory
-x[tab]the maximum number of file locks

If LIMIT is given, it is the new value of the specified resource; the
special LIMIT values `soft', `hard', and `unlimited' stand for the
current soft limit, the current hard limit, and no limit, respectively.
Otherwise, the current value of the specified resource is printed. If
no option is given, then -f is assumed.

Values are in 1024-byte increments, except for -t, which is in seconds,
-p, which is in increments of 512 bytes, and -u, which is an unscaled
number of processes.

Exit Status:
Returns success unless an invalid option is supplied or an error occurs.

521.

Wait for job completion and return exit status.

Waits for the process identified by ID, which may be a process ID or a
job specification, and reports its termination status. If ID is not
given, waits for all currently active child processes, and the return
status is zero. If ID is a a job specification, waits for all processes
in the job's pipeline.

Exit Status:
Returns the status of ID; fails if ID is invalid or an invalid option is
given.

522.

Wait for process completion and return exit status.

Waits for the specified process and reports its termination status. If
PID is not given, all currently active child processes are waited for,
and the return code is zero. PID must be a process ID.

Exit Status:
Returns the status of ID; fails if ID is invalid or an invalid option is
given.

542.

Formats and prints ARGUMENTS under control of the FORMAT.

Options:
-v var[tab]assign the output to shell variable VAR rather than
[tab][tab]display it on the standard output

FORMAT is a character string which contains three types of objects: plain
characters, which are simply copied to standard output; character escape
sequences, which are converted and copied to the standard output; and
format specifications, each of which causes printing of the next successive
argument.

In addition to the standard format specifications described in printf(1)
and printf(3), printf interprets:

%b[tab]expand backslash escape sequences in the corresponding argument
%q[tab]quote the argument in a way that can be reused as shell input
%(fmt)T output the date-time string resulting from using FMT as a format
string for strftime(3)

Exit Status:
Returns success unless an invalid option is given or a write or assignment
error occurs.