Shell programming tools (sort, uniq, tr)

sort tool

Sort according to different data types

• Character sort (default)
• Number sort

Grammar format

sort [options] parameter

Common options

• -f: Ignore case
• -b: Ignore the spaces in front of each line
• -M: Sort by month
• -n: sort by number
• -r: reverse sort
• -u: equivalent to uniq, which means that only one line of the same data is displayed
• -t: Specify the separator, use [Tab] to separate by default
• -o <output file>: dump the sorted results to the specified file
• -k: Specify the sort area

usage

Sort the accounts in the /etc/passwd file (default character sorting)

[root@server2 ~]# sort /etc/passwd

Sort the third column in the /etc/passwd file forward and backward

[root@server2 ~]# sort -n -t ":" -k 3 /etc/passwd

[root@server2 ~]# sort -n -t ":" -rk 3 /etc/passwd

Export the reverse sort results to the specified file zhfx.txt

[root@server2 ~]# sort -n -t ":" -rk 3 /etc/passwd -o zhfx.txt
[root@server2 ~]# cat zhfx.txt 

uniq tool

Common options

• -c: count
• -d; only show duplicate lines
• -u: only display lines that appear once

usage

View automatic merge of duplicate rows

[root@server2 ~]# vi testfilel
[root@server2 ~]# uniq testfilel 

Repeat count of duplicate rows

[root@server2 ~]# uniq -c testfilel

Only show duplicate rows that appear and show the number of occurrences

[root@server2 ~]# uniq -cd testfilel 

Show only lines that occur once

[root@server2 ~]# uniq -u testfilel 

tr tool

The specific command statement format of tr is

• tr [options] [parameters]

Its common options include the following

• -c: Replace all characters that do not belong to the first character set
• -d: delete all characters belonging to the first character set
• -s: represent the continuously repeated characters as a single character
• -t: first delete the characters in the first character set more than the second character set, and replace them

usage

Convert input characters from uppercase to lowercase

[root@server2 ~]# echo "GHHH" | tr 'A-Z' 'a-z'

Replace all characters that are not in the first character set

[root@server2 ~]# echo "bcd123bcd123" | tr -c bc 44

Delete all characters that are not in the first character set

[root@server2 ~]# echo "happy new year" | tr -d 'ae'  

Compress repeated characters in input

[root@server2 ~]# echo "Itttttt was an appleeeeeeeee" | tr -s 'te' 

Delete the characters in the first character set that are more than the second character set and replace them

[root@server2 ~]# echo "bcd123bcd123" | tr -t 'bcd' 'e' 
[root@server2 ~]# echo "bcd123bcd123" | tr -t 'bcd' 'eee' 
[root@server2 ~]# echo "bcd123bcd123" | tr -t 'bc' 'efg'