Notes On Some Linux Tools

sort

Use sort as follows:

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sort [options] -k<field_start[type][,field_end[type]]> [...] <input-source>

The field_start denotes the start column to sort by, and the optional field_end denotes the end column to sort by. If there is no -k, then it’s sorted on the entire line. type is a subset of options. All options are like:

• n: denotes to treat as number
• r: denotes to sort in reverse order
• s: denotes to sort stably
• f: denotes to sort case insensitively
• b: denotes to ignore blank
• o: denotes the output file
• u: denotes the uniq
• t: denotes the separator
• R: denotes to sort randomly
• c: check if sorted
• m: merge sorted inputs

If multiple <input-source>s are provided, the output will be the merged sorted result.

uniq

It works only when the duplicate lines are adjacent.

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uniq [options] <input-source>

The options are like:

• c: count the duplicates
• d: print only duplicates
• D: print duplicates all occurrences
• u: print only uniqs
• w <num>: compare with <num> limited first characters
• s <num>: skip comparing with first <num> characters
• f <num>: avoid comparing with first <num> fields

tee

It reads standard input and writes it to both standard output and files.

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tee [options] <file> [...]

The options are like:

• a: append mode
• i: ignore interrupt