awk '{ print " \x27" $1 "\x27" }' <file> | paste -sd, | fold -sw 80 ¶ definition: 'Take a list of data, add quotes and commas, and reduce the number of lines.'
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awk -F'<delimiter>' '{print <spec>}' ¶ definition: 'Extract, rearrange or transform pieces of a delimited string.'
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awk '{print FNR "\t" $0}' <file> ¶ definition: 'Append line numbers with a tab.'
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awk '{sub(/ \t+$/, "");print}' ¶ definition: 'Delete trailing whitespace from end of each line.'

awk '{sub(/^ \t+/, ""); print}' ¶ definition: 'Delete leading whitespace from front of each line.'

find -exec <command> ¶ definition: 'Execute a command on the matches.'
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variants: '''{}'' indicates the match. Terminate with ''\;''.'

find -name "<pattern>" ¶ Find objects with a name matching the pattern.

history | cut -c 8- | sort | uniq -c | sort -nr | head -n <n> ¶ definition: 'Show <n> most frequently-used commands.'

ls -lSr | tail -n 1 ¶ definition: 'Return largest file.'
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sed ':a;N;$!ba;s/\n//g' <file> ¶ definition: 'Remove all newlines from <file>.'
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sed 's_><_>\n<_g' ¶ definition: 'Quick-and-dirty solution for adding newlines to a run-on XML document.'
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tr "a-z" "A-Z" ¶ Convert lowercase to uppercase.

tr -d '<string>' ¶ Delete characters from <string>.