Interesting Command Line Tips and Tricks in Linux
Interesting Command Line Tips and Tricks in Linux
In this article we will learn some new tips and tricks in the Linux commands.
History command
Using history command, we can check what are the commands did in past.
[root@linuxhelp ~]# history
4 vim /etc/sysconfig/network
5 cd
6 fdisk -l
7 fdisk /dev/sdb
8 fdisk -l
9 fdisk -l /dev/sdb
10 fdisk -l /dev/sda
11 fdisk /dev/sda
12 fdisk -l /dev/sda
13 fdisk -s /dev/sda2
14 fdisk -l /dev/sda
15 fdisk /dev/sda
16 cd
. . . . .
. . . . .
. . . . .
990 dd if=/dev/zero of=/tmp/output.img bs=8k count=256k conv=fdatasync rm -rf /tmp/output.img
991 du -hsx * | sort -rh | head -6
992 stat fedora.iso
993 cd Desktop/
994 stat Screenshot222.png
995 pwd
996 cd /home/jagannath/
997 cd Desktop/
998 pwd
999 stat Screenshot222.png
1000 man $(ls /bin | shuf | head -1)
1001 cd
1002 clear
1003 history
If you need the history with time stamp, then execute the below command.
[root@linuxhelp ~]# HISTTIMEFORMAT=" %d/%m/%y %T "
[root@linuxhelp ~]# history
6 25/03/16 07:19:52 fdisk -l
7 25/03/16 07:19:52 fdisk /dev/sdb
8 25/03/16 07:19:52 fdisk -l
9 25/03/16 07:19:52 fdisk -l /dev/sdb
10 25/03/16 07:19:52 fdisk -l /dev/sda
11 25/03/16 07:19:52 fdisk /dev/sda
12 25/03/16 07:19:52 fdisk -l /dev/sda
13 25/03/16 07:19:52 fdisk -s /dev/sda2
14 25/03/16 07:19:52 fdisk -l /dev/sda
15 25/03/16 07:19:52 fdisk /dev/sda
16 25/03/16 07:19:52 cd
17 25/03/16 07:19:52 vim /etc/sysconfig/network
. . . . .
. . . . .
. . . . .
990 25/03/16 03:30:35 dd if=/dev/zero of=/tmp/output.img bs=8k count=256k conv=fdatasync rm -rf /tmp/output.img
991 25/03/16 03:32:50 du -hsx * | sort -rh | head -6
992 25/03/16 03:37:46 stat fedora.iso
993 25/03/16 03:38:33 cd Desktop/
994 25/03/16 03:40:14 stat Screenshot222.png
995 25/03/16 03:40:32 pwd
996 25/03/16 03:40:42 cd /home/jagannath/
997 25/03/16 03:40:55 cd Desktop/
998 25/03/16 03:40:58 pwd
999 25/03/16 03:41:08 stat Screenshot222.png
1000 25/03/16 03:44:23 man $(ls /bin | shuf | head -1)
1001 25/03/16 07:19:55 cd
1002 25/03/16 07:19:58 clear
1003 25/03/16 07:20:13 history
1004 25/03/16 07:22:59 HISTTIMEFORMAT=" %d/%m/%y %T "
1005 25/03/16 07:23:08 history
Add the below line to ~/.bashrc, If you need to append this change permanently.
[root@linuxhelp ~]# export HISTTIMEFORMAT=" %d/%m/%y %T "
[root@linuxhelp ~]# source ~/.bashrc
Explanation of commands are,
History denotes as GNU History Library.
HISTIMEFORMAT is the Environmental Variable.
%d denotes as Day.
%m denotes as Month.
%y denotes as Year.
%T denotes the Time Stamp.
source represents in short send the contents of file to shell.
.bashrc denotes a shell script, if it started interactively then BASH start to run.
dd command
Using dd command, we can check disk write speed.
[root@linuxhelp ~]# dd if=/dev/zero of=/tmp/output.img bs=8k count=256k conv=fdatasync rm -rf /tmp/output.img
262144+0 records in
262144+0 records out
2147483648 bytes (2.1 GB) copied, 20.7229 s, 104 MB/s
Explanation of commands are,
dd mentions Convert and Copy a file.
if=/dev/zero denotes Read the file and not stdin.
of=/tmp/output.img command used to Write to file and not stdout.
bs used to Read and Write maximum upto M bytes, at one time.
count used to Copy N input block.
conv is the command line used to Convert the file as per comma separated symbol list.
rm used to Removes files and folder.
-rf used to (-r) removes directories and contents recursively and (-f) Force the removal without prompt.
du command
Using du command, we can check first six files that occupying more space in your system.
[root@linuxhelp ~]# du -hsx * | sort -rh | head -6
287M gitlab-7.7.1_omnibus.5.4.1.ci-1.el6.x86_64.rpm
11M j
11M home
4.4M gitlab-workhorse
3.3M mantisbt-1.2.19.zip
116K install.log
Explanation of commands are,
du needs to Estimate file space usages.
-hsx used to (-h) Human Readable Format, (-s) Summaries Output, (-x) One File Format, skip directories on other file format.
sort command is used to Sort text file lines.
-rh used to (-r) Reverse the result of comparison, (-h) for compare human readable format.
head is the command used to output first n lines of file.
stat command
Using stat command, we can get the statistics related to a file.
stat filename_ext (viz., stat abc.pdf)
[root@linuxhelp ~]# cd /tmp
[root@linuxhelp tmp]# stat csf.tgz
File: `csf.tgz'
Size: 688544 Blocks: 1352 IO Block: 4096 regular file
Device: 802h/2050d Inode: 693045 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2016-03-17 10:09:01.858006913 +0530
Modify: 2016-02-25 23:23:17.000000000 +0530
Change: 2016-03-17 09:59:49.626007416 +0530
Another Example:
[root@linuxhelp tmp]# stat autoinstaller3.log
File: `autoinstaller3.log'
Size: 12020 Blocks: 24 IO Block: 4096 regular file
Device: 802h/2050d Inode: 656910 Links: 1
Access: (0600/-rw-------) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2016-03-19 07:45:51.854643390 +0530
Modify: 2016-03-19 08:35:23.938004452 +0530
Change: 2016-03-19 08:35:23.938004452 +0530
man command
Using man command, we can generate random man pages and that helps to learn new about linux.
[root@linuxhelp tmp]# man $(ls /bin | shuf | head -1)
OSTNAME(1) Linux Programmer’ s Manual HOSTNAME(1)
NAME
hostname - show or set the system’ s host name
domainname - show or set the system’ s NIS/YP domain name
dnsdomainname - show the system’ s DNS domain name
nisdomainname - show or set system’ s NIS/YP domain name
ypdomainname - show or set the system’ s NIS/YP domain name
SYNOPSIS
hostname [-v] [-a] [--alias] [-d] [--domain] [-f] [--fqdn] [-A] [--all-
fqdns] [-i] [--ip-address] [-I] [--all-ip-addresses] [--long] [-s]
[--short] [-y] [--yp] [--nis]
hostname [-v] [-F filename] [--file filename] [hostname]
domainname [-v] [-F filename] [--file filename] [name]
nodename [-v] [-F filename] [--file filename] [name]
hostname [-v] [-h] [--help] [-V] [--version]
dnsdomainname [-v]
nisdomainname [-v]
ypdomainname [-v]
:q----> to quit
Explanation of commands are,
man command is used to display Linux Man pages.
ls used to Linux Listing Commands.
/bin denotes System Binary file Location.
shuf used to Generate Random Permutation.
head used to Output first n line of file.
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