shell
Last updated
Last updated
cmd | result |
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https://www.gnu.org/software/bash/manual/html_node/Pattern-Matching.html
https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html#Shell-Parameter-Expansion
type | example | result | More |
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https://en.wikipedia.org/wiki/Here_document#Unix_shells
$0
./t.sh
$(basename $0)
t.sh
$(basename $0 .sh)
t
${PWD##*/}
parent_dir_name
Length
echo ${#SHELL}
9
${parameter:-$var}
${NULL:-$SHELL}
/bin/bash
${parameter:-word}
echo ${SHELL:-ignored}
/bin/bash
[ -z "${COLUMNS:-}" ] && COLUMNS=80 ; echo $COLUMNS
${parameter:=word}
unset a ; echo ${a:=b} ; echo $a
b b
${VAR:OFFSET:KEEP}
echo ${SHELL:0:4}
/bin
${VAR/PATTERN/NEW}
echo ${SHELL/b/}
/in/bash
${VAR//PATTERN/NEW}
echo ${SHELL//b/}
/in/ash
${VAR#beginning}
echo ${SHELL#*/}
bin/bash
${VAR##beginning}
echo ${SHELL##*/}
bash
${VAR%trailing}
${SHELL%/*h}
/bin