Basic Linux Commands for Text Processing

Linux command line tools are really useful for text processing. This article will conclude some basic commands for that purpose.

1. wc : count lines and words

#count how many lines a file has.
wc -l filename

#count how many words a file has.
wc -w filename

#count how many bytes a file has.
wc -c filename

2. sort : sort the lines of a file

#sort the lines of a file
sort filename

3. uniq : delete the duplicated line of a sorted file

#In general, we use sort command before uniq. The result can be output to some file
sort filename | uniq > outputFile #### 4. expand : expand each tab to four spaces (unexpand can do reverse, but I did not success..)
expand filename #### 5. cut : the cut utility cuts out selected portions of each line (as specified by list) from each file and writes them to the standard output.
#Extract users' login names and shells from the system passwd(5) file as ``name:shell'' pairs:
cut -d : -f 1,7 /etc/passwd

#Show the names and login times of the currently logged in users:
who | cut -c 1-16,26-38

This command may be a little bit hard to use. Try awk instead. For example:

wc -l filename | awk {'print $1'}

My Pocket has one Chinese article that introduces some more commands.