Bash: Difference between revisions
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==Swapping stdin and stdout == | == Swapping stdin and stdout == | ||
command 3>&1 1>&2 2>&3 | command 3>&1 1>&2 2>&3 | ||
== extracting vars from strings == | |||
example 1: | |||
<pre> | |||
#!/usr/bin/env bash | |||
str1="the value of var1=test, the value of var2=testing, the final value of var3=testing1" | |||
re='(^|[[:space:]])([[:alpha:]][[:alnum:]]*)=([^, ]+)([, ]|$)(.*)' | |||
remaining=$str1 | |||
while [[ $remaining =~ $re ]]; do | |||
varname=${BASH_REMATCH[2]} | |||
value=${BASH_REMATCH[3]} | |||
remaining=${BASH_REMATCH[5]} | |||
printf -v "$varname" %s "$value" | |||
done | |||
# show current values to demonstrate that variables were really assigned | |||
declare -p var1 var2 var3 | |||
</pre> | |||
example 2: | |||
extract the --port=XX section from what was handed to the script, where XX is a number. | |||
<pre> | |||
#!/bin/bash | |||
#re="--port=(.*?) " | |||
re="--port=([0-9]*?) " | |||
if [[ $@ =~ $re ]]; then | |||
echo "match" | |||
echo zero ${BASH_REMATCH[0]} | |||
echo one ${BASH_REMATCH[1]} | |||
echo two ${BASH_REMATCH[2]} | |||
echo three ${BASH_REMATCH[3]} | |||
else | |||
echo "no match" | |||
fi | |||
</pre> | |||
== Also See == | == Also See == | ||
[[. | [[.bashrc]] | ||
[[Stupid Shell Tricks]] | [[Stupid Shell Tricks]] |
Latest revision as of 18:16, 31 December 2019
Swapping stdin and stdout
command 3>&1 1>&2 2>&3
extracting vars from strings
example 1:
#!/usr/bin/env bash str1="the value of var1=test, the value of var2=testing, the final value of var3=testing1" re='(^|[[:space:]])([[:alpha:]][[:alnum:]]*)=([^, ]+)([, ]|$)(.*)' remaining=$str1 while [[ $remaining =~ $re ]]; do varname=${BASH_REMATCH[2]} value=${BASH_REMATCH[3]} remaining=${BASH_REMATCH[5]} printf -v "$varname" %s "$value" done # show current values to demonstrate that variables were really assigned declare -p var1 var2 var3
example 2:
extract the --port=XX section from what was handed to the script, where XX is a number.
#!/bin/bash #re="--port=(.*?) " re="--port=([0-9]*?) " if [[ $@ =~ $re ]]; then echo "match" echo zero ${BASH_REMATCH[0]} echo one ${BASH_REMATCH[1]} echo two ${BASH_REMATCH[2]} echo three ${BASH_REMATCH[3]} else echo "no match" fi