mirror of https://github.com/tLDP/LDP
41 lines
1.0 KiB
Bash
41 lines
1.0 KiB
Bash
#!/bin/bash
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# subst.sh: a script that substitutes one pattern for
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#+ another in a file,
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#+ i.e., "sh subst.sh Smith Jones letter.txt".
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# Jones replaces Smith.
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ARGS=3 # Script requires 3 arguments.
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E_BADARGS=85 # Wrong number of arguments passed to script.
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if [ $# -ne "$ARGS" ]
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then
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echo "Usage: `basename $0` old-pattern new-pattern filename"
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exit $E_BADARGS
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fi
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old_pattern=$1
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new_pattern=$2
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if [ -f "$3" ]
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then
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file_name=$3
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else
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echo "File \"$3\" does not exist."
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exit $E_BADARGS
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fi
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# -----------------------------------------------
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# Here is where the heavy work gets done.
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sed -e "s/$old_pattern/$new_pattern/g" $file_name
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# -----------------------------------------------
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# 's' is, of course, the substitute command in sed,
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#+ and /pattern/ invokes address matching.
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# The 'g,' or global flag causes substitution for EVERY
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#+ occurence of $old_pattern on each line, not just the first.
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# Read the 'sed' docs for an in-depth explanation.
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exit $? # Redirect the output of this script to write to a file.
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