UNIX-1.4 Sort and Sed Commands

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sort – sort file
sort -t, -k1 file1 – sort file1 by column 1, delimited by comma (,)
sort -r -t, -k1 file1 – in reverse
sort -n -t, -k1 file1 – sort by numerical value
sort -f file1 – case insensitive sort
sort -t’|’ +0 -2 – sort by the first 2 fields, starting from 0+1th field and end at 2nd field.

sed – special editor
sed ‘s/pattern/replacement/gi’ – search and replacement globally and case insensitively
sed ‘s/pattern/&replacement/gi’ – & represents the pattern found
sed ‘s/\(group\)pattern/\1/gi’ – \1 contains value of 1st group
sed ‘s/hello/bye/2g’ – replacements second occurrence of hello
sed ‘/pattern/p’ – will print out occurrences of pattern
sed -e ‘command1’ -e ‘command2’ – run multiple commands
sed ‘s/'”$VAR”‘/replacement/’ – using external variables in sed
sed ‘2 s/pattern/replacement/’ – replace only for line 2. you can also specify line range, 1,10
sed ‘/pattern1/ s/pattern2/replacement/’ – find pattern1, for those lines, replace pattern2 with replacement
sed ‘/start/,/end/ s/pattern/replacement/’ – using patterns as line number range. you can also mix line number with pattern
sed ‘1,10d’ – deletes line 1 to 10. you can also mix pattern range as well
sed ‘100,$d’ – delete from line 100 to end of file
sed ‘100,$!d’ – delete from line 1 to line 100. ! means inverse operation.
sed ‘y/ABC/abc/’ – replacement each character with corresponding characters

regular expression
[0-9a-z]* – match 0 or more alphanumeric characters
[0-9a-z]+ – match 1 or more alphanumeric characters
[^a-z] – any character does not contain a-z