1. Sort Your Output
Problem
You would like output in a stored order. but you don't want to write a custom sort function for your program or shell script.
Solution
Use the sort utility.You can sort one or more files by putting the file name on the command line:
$ sort file1.txt file2.txt myotherfile.xyz
With no filenames on the command, sort will read from standard input so you can pipe the output from a previous command into sort:
$ somecommands | sort
There a few options to sort,but two of the three most worth remembering are :
- sort -r (to reverse the order of the sort)
- sort -f (to fold lower- and uppercase characters together)
- sort --ignore-case
2.How to sorting numbers?
Problem
When sorting numeric data you notice that the order doesn't seem right
[root@DBAMAXWELL cp8]# sort somedata
2
200
21
250
Solution
You need to tell sort that the data should be sorted as numbers. specify a numeric sort with the -n option:
[root@DBAMAXWELL cp8]# sort -n somedata
2
21
200
250
[root@DBAMAXWELL cp8]#
sort -rn can be very handy in giving you a descending frequency list of something when combined with uniq -c.
[root@DBAMAXWELL cp8]# cut -d ":" -f7 /etc/passwd | sort | sort | uniq -c | sort -rn
27 /sbin/nologin
5 /bin/bash
1 /sbin/shutdown
1 /sbin/halt
1 /bin/sync
1 /bin/false
[root@DBAMAXWELL cp8]#
3.How to sorting IP Addresses ?
[root@DBAMAXWELL cp8]# sort -t . -k 1,1n -k 2,2n -k 3,3n -k 4,4n ipaddr.list
10.0.0.2
10.0.0.5
10.0.0.20
192.168.0.2
192.168.0.4
192.168.0.12
[root@DBAMAXWELL cp8]#
4.How to cutting out parts of your output?
Problem
You need to look at only part of your fixed-width or column-based data. You'd like to take a subset of it ,based on the column position.
Solution
Use the cut command with the -c option to take particular columns
[root@DBAMAXWELL cp8]# ps -l
F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD
0 S 0 86528 86527 0 80 0 - 6886 - pts/1 00:00:00 bash
4 S 0 86689 86528 0 80 0 - 34404 - pts/1 00:00:00 su
4 S 0 87049 86690 0 80 0 - 34404 - pts/1 00:00:00 su
4 S 0 87050 87049 0 80 0 - 6918 - pts/1 00:00:00 bash
0 R 0 91869 87050 0 80 0 - 11372 - pts/1 00:00:00 ps
[root@DBAMAXWELL cp8]# ps -l | cut -c12-15
P
865
866
870
870
918
918
[root@DBAMAXWELL cp8]# ps -elf | cut -c58-
IME TTY TIME CMD
r14 ? 00:00:55 /usr/lib/systemd/systemd --switched-root --system --deserialize 17
r14 ? 00:00:00 [kthreadd]
r14 ? 00:00:00 [rcu_gp]
r14 ? 00:00:00 [rcu_par_gp]
r14 ? 00:00:00 [kworker/0:0H-events_highpri]
r14 ? 00:00:00 [mm_percpu_wq]
r14 ? 00:00:00 [rcu_tasks_rude_]
r14 ? 00:00:00 [rcu_tasks_trace]
r14 ? 00:00:07 [ksoftirqd/0]
r14 ? 00:01:31 [rcu_sched]
r14 ? 00:00:00 [migration/0]
5.How to removing duplicate lines?
Problem:
After selecting and/or sorting some data you notice that there are many duplicate lines in your results.You'd like to get ride of the duplicates,so that you can see just the unique value.
Solution:
If you've just been sorting your output,add the -u option to the sort command:
- $somesequence | sort -u
If you aren't running sort,just pip the output into uniq
- somesequence > myfile
- uniq myfile
6.How to compressing Files
Problem:
You need to compress some files and aren't sure of the best way to do it.
Solution:
$ tar cf tarball_name.tar directory_of_files
$ gzip tarball_name.tar
7.How to uncompressing Files
Problem
You need to uncompress one or more files ending in extension like tar,tar.gz,gz.tgz,Z,or zip
Solution
7.Counting Lines,Words,or Characters in a File
Problem:
You need to know how many lines,words,or characters are in a given file
Solution:
[root@DBAMAXWELL cp8]# wc data_file
8 132 754 data_file
[root@DBAMAXWELL cp8]# wc -l data_file
8 data_file
[root@DBAMAXWELL cp8]# wc -w data_file
132 data_file
[root@DBAMAXWELL cp8]# wc -c data_file
754 data_file
[root@DBAMAXWELL cp8]# ls -l data_file
-rw-r--r-- 1 root root 754 Mar 17 18:38 data_file
[root@DBAMAXWELL cp8]#
8.How to Rewrapping Paragraphs
Problem:
You have some text with lines that are too long,or too short,so you'd like to re-wrap them to be more readable.
Solution:
Use the fmt command, optionally with a goal and maximum line length.
[root@DBAMAXWELL cp8]# fmt mangled_text
[root@DBAMAXWELL cp8]# fmt 55 60 mangled_text
9.How to doing more with less
Problem:
You'd like to take better advantage of the features of the less paper.
Solution:
Read the less manage and use the $LESS variable with ~/.lessfilter and ~/.lesspipe files.