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← Revision 25 as of 2020-02-04 18:35:41 ⇥
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*sigh* put the common, simple versions first.
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== How do I process options in a bash script? == For example, how do I code my bash script to accept a bunch of options like |
== Common utility functions (warn, die) == (If you were looking for option processing, see [[BashFAQ/035]].) Bash and sh don't offer a `die` builtin command like Perl does, but it's common to use a `die` function in scripts. You just have to write one yourself. Most people who write a `die` function like to keep it simple. There are two common varieties: one that only takes a message to print, and one that takes a message and an exit status value. |
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foobar -a --busy --include something | # Usage: die message ... die() { printf '%s\n' "$*" >&2 exit 1 } |
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First up, there are some [[http://www.gnu.org/software/libtool/manual/libc/Argument-Syntax.html][GNU and POSIX standards]] for how to do this. | {{{ # Usage: die exit_status message ... die() { rc=$1 shift printf '%s\n' "$*" >&2 exit "$rc" } }}} Some people like fancier functions. If you like fancier functions, here are some variants: {{{ ## # warn: Print a message to stderr. # Usage: warn "format" ["arguments"...] # warn() { local fmt=$1 shift printf "script_name: $fmt\n" "$@" >&2 } ### ### The following three "die" functions ### depend on the above "warn" function. ### ## # die (simple version): Print a message to stderr # and exit with the exit status of the most recent # command. # Usage: some_command || die "message" ["arguments"...] # die () { local st=$? warn "$@" exit "$st" } ## # die (explicit status version): Print a message to # stderr and exit with the exit status given. # Usage: if blah; then die status_code "message" ["arguments"...]; fi # die() { local st=$1 shift warn "$@" exit "$st" } ## # die (optional status version): Print a message to # stderr and exit with either the given status or # that of the most recent command. # Usage: some_command || die [status code] "message" ["arguments"...] # die() { local st=$? if [[ $1 != *[^0-9]* ]]; then st=$1 shift fi warn "$@" exit "$st" } }}} {{{ ## # warn: Print a message to stderr. # Usage: warn "message" # warn() { printf '%s\n' "$@" >&2 } ## # die (optional status version): Print a message to # stderr and exit with either the given status or # that of the most recent command. # Usage: some_command || die "message" [status code] # some_command && die "message" [status code] die() { local st=$? case $2 in *[^0-9]*|'') :;; *) st=$2;; esac warn "$1" exit "$st" } }}} Since it's your script, you get to decide how fancy you want to make it. |
Common utility functions (warn, die)
(If you were looking for option processing, see BashFAQ/035.) Bash and sh don't offer a die builtin command like Perl does, but it's common to use a die function in scripts. You just have to write one yourself. Most people who write a die function like to keep it simple. There are two common varieties: one that only takes a message to print, and one that takes a message and an exit status value.
# Usage: die message ... die() { printf '%s\n' "$*" >&2 exit 1 }
# Usage: die exit_status message ... die() { rc=$1 shift printf '%s\n' "$*" >&2 exit "$rc" }
Some people like fancier functions. If you like fancier functions, here are some variants:
## # warn: Print a message to stderr. # Usage: warn "format" ["arguments"...] # warn() { local fmt=$1 shift printf "script_name: $fmt\n" "$@" >&2 } ### ### The following three "die" functions ### depend on the above "warn" function. ### ## # die (simple version): Print a message to stderr # and exit with the exit status of the most recent # command. # Usage: some_command || die "message" ["arguments"...] # die () { local st=$? warn "$@" exit "$st" } ## # die (explicit status version): Print a message to # stderr and exit with the exit status given. # Usage: if blah; then die status_code "message" ["arguments"...]; fi # die() { local st=$1 shift warn "$@" exit "$st" } ## # die (optional status version): Print a message to # stderr and exit with either the given status or # that of the most recent command. # Usage: some_command || die [status code] "message" ["arguments"...] # die() { local st=$? if [[ $1 != *[^0-9]* ]]; then st=$1 shift fi warn "$@" exit "$st" }
## # warn: Print a message to stderr. # Usage: warn "message" # warn() { printf '%s\n' "$@" >&2 } ## # die (optional status version): Print a message to # stderr and exit with either the given status or # that of the most recent command. # Usage: some_command || die "message" [status code] # some_command && die "message" [status code] die() { local st=$? case $2 in *[^0-9]*|'') :;; *) st=$2;; esac warn "$1" exit "$st" }
Since it's your script, you get to decide how fancy you want to make it.