mirror of
git://git.code.sf.net/p/zsh/code
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259 lines
7 KiB
Text
259 lines
7 KiB
Text
# function zargs {
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#
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# This function works like GNU xargs, except that instead of reading lines
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# of arguments from the standard input, it takes them from the command
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# line. This is possible/useful because, especially with recursive glob
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# operators, zsh often can construct a command line for a shell function
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# that is longer than can be accepted by an external command.
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#
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# Like xargs, zargs exits with the following status:
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# 0 if it succeeds
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# 123 if any invocation of the command exited with status 1-125
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# 124 if the command exited with status 255
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# 125 if the command is killed by a signal
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# 126 if the command cannot be run
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# 127 if the command is not found
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# 1 if some other error occurred.
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#
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# The full set of GNU xargs options is supported (see help text below);
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# although --eof and --max-lines therefore have odd names, they have
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# analogous meanings to their xargs counterparts. Also zargs --help is
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# a lot more helpful than xargs --help, at least as of xargs 4.1.
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#
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# Note that "--" is used both to end the options and to begin the command,
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# so to specify some options along with an empty set of input-args, one
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# must repeat the "--" as TWO consecutive arguments, e.g.:
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# zargs --verbose -- -- print There are no input-args
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# If there is at least one input-arg, the first "--" may be omitted:
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# zargs -p -i one -- print There is just {} input-arg
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# Obviously, if there is no command, the second "--" may be omitted:
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# zargs -n2 These words will be echoed in five lines of two
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#
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# BUGS:
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#
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# "Killed by a signal" is determined by the usual shell rule that $? is
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# the signal number plus 128, so zargs can be fooled by a command that
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# explicitly exits with 129+. Also, zsh prior to 4.1.x returns 1 rather
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# than 127 for "command not found" so this function incorrectly returns
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# 123 in that case if used with zsh 4.0.x.
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#
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# With the --max-procs option, zargs may not correctly capture the exit
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# status of the backgrounded jobs, because of limitations of the "wait"
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# builtin. If the zsh/parameter module is not available, the status is
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# NEVER correctly returned, otherwise the status of the longest-running
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# job in each batch is captured.
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#
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# Also because of "wait" limitations, --max-procs spawns max-procs jobs,
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# then waits for all of those, then spawns another batch, etc.
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#
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emulate -L zsh || return 1
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local -a opts eof n s l P i
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local ZARGS_VERSION="1.3"
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if zparseopts -a opts -D -- \
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-eof::=eof e::=eof \
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-exit x \
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-help \
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-interactive p \
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-max-args:=n n:=n \
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-max-chars:=s s:=s \
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-max-lines::=l l::=l \
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-max-procs:=P P:=P \
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-no-run-if-empty r \
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-null 0 \
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-replace::=i i::=i \
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-verbose t \
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-version
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then
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if (( $opts[(I)--version] ))
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then
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print -u2 zargs version $ZARGS_VERSION zsh $ZSH_VERSION
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fi
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if (( $opts[(I)--help] ))
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then
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>&2 <<-\HELP
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Usage: zargs [options --] [input-args] [-- command [initial-args]]
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If command and initial-args are omitted, "print -r --" is used.
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Options:
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--eof[=eof-str], -e[eof-str]
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Change the end-of-input-args string from "--" to eof-str. If
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given as --eof=, an empty argument is the end; as --eof or -e,
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with no (or an empty) eof-str, all arguments are input-args.
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--exit, -x
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Exit if the size (see --max-chars) is exceeded.
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--help
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Print this summary and exit.
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--interactive, -p
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Prompt before executing each command line.
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--max-args=max-args, -n max-args
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Use at most max-args arguments per command line.
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--max-chars=max-chars, -s max-chars
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Use at most max-chars characters per command line.
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--max-lines[=max-lines], -l[max-lines]
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Use at most max-lines of the input-args per command line.
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This option is misnamed for xargs compatibility.
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--max-procs=max-procs, -P max-procs
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Run up to max-procs command lines in the background at once.
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--no-run-if-empty, -r
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Do nothing if there are no input arguments before the eof-str.
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--null, -0
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Split each input-arg at null bytes, for xargs compatibility.
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--replace[=replace-str], -i[replace-str]
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Substitute replace-str in the initial-args by each initial-arg.
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Implies --exit --max-lines=1.
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--verbose, -t
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Print each command line to stderr before executing it.
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--version
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Print the version number of zargs and exit.
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HELP
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return 0
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fi
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if (( $opts[(I)--version] ))
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then
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return 0
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fi
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if (( $#i ))
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then
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l=1
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i=${${i##-(i|-replace(=|))}:-\{\}}
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opts[(r)-x]=-x
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# The following is not how xargs is documented,
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# but GNU xargs does behave as if -i implies -r.
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opts[(r)-r]=-r
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fi
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if (( $#P ))
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then
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P=${${P##-(P|-max-procs(=|))}:-1}
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if [[ x${P} != x$[P] ]]
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then
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print -u2 zargs: invalid number for -P option
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return 1
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fi
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else P=1
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fi
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else
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return 1
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fi
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local -i end c=0
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if [[ $eof == -(e|-eof) ]]; then ((end=ARGC+1))
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elif (( $#eof )); then end=$argv[(i)${eof##-(e|-eof=)}]
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else end=$argv[(i)--]
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fi
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local -a args call command; command=( ${argv[end+1,-1]} )
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if (( $opts[(I)-(null|0)] ))
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then set -- ${(ps:\000:)argv[1,end-1]}
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else set -- $argv[1,end-1]
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fi
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if [[ -n $command ]]
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then (( c = $#command - 1 ))
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else command=( print -r -- )
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fi
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local wait bg
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local execute='
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if (( $opts[(I)-(-interactive|p)] ))
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then read -q "?$call?..." || continue
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elif (( $opts[(I)-(-verbose|t)] ))
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then print -u2 -r -- "$call"
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fi
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eval "{
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\$call
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} $bg"'
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local ret=0 analyze='
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case $? in
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(0) ;;
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(<1-125>|128) ret=123;;
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(255) return 124;;
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(<129-254>) return 125;;
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(126) return 126;;
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(127) return 127;;
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(*) return 1;;
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esac'
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if (( ARGC == 0 ))
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then
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if (( $opts[(I)-(-no-run-if-empty|r)] ))
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then return 0
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else
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call=($command)
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# Use "repeat" here so "continue" won't complain.
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repeat 1 eval "$execute ; $analyze"
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return $ret
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fi
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fi
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n=${${n##-(n|-max-args(=|))}:-$[ARGC+c]}
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if (( n > c ))
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then (( n -= c ))
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else
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print -u2 zargs: argument list too long
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return 1
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fi
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P=${${P##-(P|-max-procs(=|))}:-1}
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if (( P != 1 && ARGC > 1 ))
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then
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# These setopts are necessary for "wait" on multiple jobs to work.
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setopt nonotify nomonitor
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bg='&'
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if zmodload -i zsh/parameter 2>/dev/null
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then
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wait='wait %${(k)^jobstates[(R)running:*]}'
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else
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wait='wait'
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fi
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fi
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s=${${s##-(s|-max-chars(=|))}:-20480}
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l=${${l##-(l|-max-lines(=|))}:-${${l[1]:+1}:-$ARGC}}
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# Everything has to be in a subshell just in case of backgrounding jobs,
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# so that we don't unintentionally "wait" for jobs of the parent shell.
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(
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while ((ARGC))
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do
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if (( P == 0 || P > ARGC ))
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then (( P = ARGC ))
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fi
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repeat $P
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do
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((ARGC)) || break
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for (( end=l; end && ${(c)#argv[1,end]} > s; end/=2 )) :
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(( end > n && ( end = n ) ))
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args=( $argv[1,end] )
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shift $((end > ARGC ? ARGC : end))
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if (( $#i ))
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then call=( ${command/$i/$args} )
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else call=( $command $args )
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fi
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if (( ${(c)#call} > s ))
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then
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print -u2 zargs: cannot fit single argument within size limit
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# GNU xargs exits here whether or not -x,
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# but that just makes the option useless.
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(( $opts[(I)-(-exit|x)] )) && return 1
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continue
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else
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eval "$execute"
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fi
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done
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eval "$wait
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$analyze"
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done
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return $ret
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)
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# }
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