mirror of https://github.com/tLDP/LDP
74 lines
1.6 KiB
Bash
74 lines
1.6 KiB
Bash
#!/bin/bash
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# alias.sh
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shopt -s expand_aliases
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# Must set this option, else script will not expand aliases.
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# First, some fun.
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alias Jesse_James='echo "\"Alias Jesse James\" was a 1959 comedy starring Bob Hope."'
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Jesse_James
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echo; echo; echo;
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alias ll="ls -l"
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# May use either single (') or double (") quotes to define an alias.
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echo "Trying aliased \"ll\":"
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ll /usr/X11R6/bin/mk* #* Alias works.
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echo
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directory=/usr/X11R6/bin/
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prefix=mk* # See if wild card causes problems.
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echo "Variables \"directory\" + \"prefix\" = $directory$prefix"
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echo
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alias lll="ls -l $directory$prefix"
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echo "Trying aliased \"lll\":"
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lll # Long listing of all files in /usr/X11R6/bin stating with mk.
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# An alias can handle concatenated variables -- including wild card -- o.k.
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TRUE=1
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echo
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if [ TRUE ]
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then
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alias rr="ls -l"
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echo "Trying aliased \"rr\" within if/then statement:"
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rr /usr/X11R6/bin/mk* #* Error message results!
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# Aliases not expanded within compound statements.
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echo "However, previously expanded alias still recognized:"
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ll /usr/X11R6/bin/mk*
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fi
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echo
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count=0
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while [ $count -lt 3 ]
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do
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alias rrr="ls -l"
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echo "Trying aliased \"rrr\" within \"while\" loop:"
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rrr /usr/X11R6/bin/mk* #* Alias will not expand here either.
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# alias.sh: line 57: rrr: command not found
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let count+=1
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done
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echo; echo
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alias xyz='cat $0' # Script lists itself.
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# Note strong quotes.
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xyz
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# This seems to work,
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#+ although the Bash documentation suggests that it shouldn't.
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#
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# However, as Steve Jacobson points out,
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#+ the "$0" parameter expands immediately upon declaration of the alias.
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exit 0
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