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Awesome Bash Commands

A curated list of awesome Bash useful commands. Inspired by awesome-shell and bash-handbook.

Table of Contents

• Files and directories
• Paths
• Devices
• Users and Groups
• Date & Time
• Network
• Miscellaneous
• Other Awesome Lists

Files and directories

List files sorted by extension

ls -l -X
# Or
ls -l --sort=extension

Count number of files within a directory

ls -1 ./my-directory | wc -l

Note: use -a to include also dot files.

Create a symbolic link for one directory or file

ln -s /var/www/html ~/www
ln -s ~/my/large/path/file.txt ~/myfile.txt

Change permissions for a symbolic link only

chmod -h 770 ~/www
chown -h www-data:www-data ~/www

Find octal permissions of one file or directory

stat -c "%a %n" /var/www/html
# 770 /var/www/html

Add sticky permissions to one directory and subdirectories

find /var/www/html -type d -exec chmod g+s {} \

Note: Any new file created will have the same permissions as the root folder

Create one empty file in current directory and subdirectories

find ./my/current/directory -type d -exec touch {}/.gitignore \;

Delete one specific file of current directory and subdirectories

find ./my/current/directory -name ".gitignore" -type f -delete

Delete all content of one directory but except one in specific

find ./my-directory -mindepth 1 ! -regex '^./my-directory/data\(/.*\)?' -delete

Copy file content to clipboard

Copy shell command output to clipboard

cat myfile.txt | xclip -selection c

Copy entire directory to destination

cp -avr /my/current/directory /destination/directory
# Or
rsync -av /my/current/directory /destination/directory

Copy entire directory files only to destination with exclude option

rsync -har --progress --exclude .git /current/directory/. /destination/directory

Transfer an entire directory content to a remote destination

Note: It's necessary to setup a SSH connection. You can use a SSH Config file.

rsync -hrtpluz --progress --stats my-current-directory/. my-remote-server:/var/data/my-remote-dir

Options used above:

-h,                  output numbers in a human-readable format 
-r                   recurse into directories
-t, --times          preserve modification times
-p, --perms          preserve permissions
-l, --links          copy symlinks as symlinks
-u, --update         skip files that are newer on the receiver
-z, --compress       compress file data during the transfer
--progress           show progress during transfer
--stats              give some file-transfer stats

Show the space usage of file or directory

Show the space usage of file or directory (recursive) in human readable format.

du -sh /var/log/dnf.librepo.log
# 4,1M	/var/log/dnf.librepo.log

du -sh /var/log
# 2,2G	/var/log

Show size of one symbolic link (file or directory)

du -Hsh $(which dart)
# 21M	/usr/local/bin/dart

Show space usage of directories and files ordered by size

du -sh /var/data/software/app/* | sort -rh
# 1.1G	/var/data/software/app/backups
# 223M	/var/data/software/app/logs
# 125M	/var/data/software/app/attachments
# 70M	/var/data/software/app/recovery
# 1.2M	/var/data/software/app/shared-home
# 592K	/var/data/software/app/viewfile
# 12K	/var/data/software/app/journal
# 4.0K	/var/data/software/app/bundled-plugins
# 0	    /var/data/software/app/lock

Show top ten of biggest directories

du -hS /home/user/some/directory | sort -rh | head -10
# 90G	/home/user/some/directory/big-dir
# 10G	/home/user/some/directory/subdir/another-big-dir
# ...

Delete all files in directory by pattern

find /usr/local/apache/logs/archive/ -name '*2017.gz' -delete

Move files by pattern

This command move all *.js files into *.ts files (move equivalent)

find src/ -type f -name "*.js" -exec bash -c 'mv {} `echo {} | sed -e "s/.js/.ts/g"`' \;

Compress files by pattern using tar and gzip

Command bellow compress a group of files by pattern using tar and gzip compression into a new file like FILE_NAME.tar.gz. No sorting guaranteed.

# Input files:
# src/file1.log.01
# src/file1.log.02
# src/file1.log.03

find src/ -type f -name "file1.log.*" -exec bash -c "tar cf - {} | gzip -9 > {}.tar.gz" \;

# Or using find -exec

find src/ -maxdepth 1 -type f -name "file1.log.*" -exec sh -c "tar cf - {} | gzip -9 > tarballs/{}.tar.gz && echo '{} (compressed)'" \;

# Output files:
# src/file1.log.01.tar.gz
# src/file1.log.02.tar.gz
# src/file1.log.03.tar.gz

Optimizing Tar/Gzip archive size by changing content files order

find directory/* -print | rev | sort | rev | \
      tar --create --no-recursion --files-from - | \
      gzip -c > directory.tar.gz

Motivated by https://news.ycombinator.com/item?id=24221498

Alternative sorting in ascending way:

find . -type f -name  "file1.log.*" | sort -n | xargs -I{} sh -c "tar cf - {} | gzip -9 > {}.tar.gz && echo '{} (compressed)'" \;

Tip: Use -maxdepth flag in order to limit directory levels finding.

Compress a directory using tar and gzip

tar -zcvf my_dir.tar.gz my-dir/

List content of a tar and gzip file without extracting it

tar -tvf my_dir.tar.gz | less

Create a temporary directory with prefix

mktemp -dt "my-prefix"

Clean temporary directory

rm -rf /tmp/* /tmp/.*

Calculate gzip size of one no compressed file

gzip -c FILENAME.txt | wc -c | awk '{
if ($1 > 1000 ^ 3) {
  print($1 / (1000 ^ 3)"G")
} else if ($1 > 1000 ^ 2) {
  print($1 / (1000 ^ 2)"M")
} else if ($1 > 1000) {
  print($1 / 1000"K")
} else {
  print($1)"b"
}}'

# 560K

Split out a specific file into more small files by number of lines

split -d -l 200000 ./big_file.log small_file.log.

# Output files in current directory:
# small_file.log.01
# small_file.log.02
# small_file.log.03
# ....

Notes:

• smallfile.log. is a custom suffix for file names.
• 200000 is a custom number of lines per file.

Get only the number of lines of one specific file

wc -l big_file.log | sed -E "s/([a-z\-\_\.]|[[:space:]]*)//g"

# 9249133

Paths

Show the full path of a command

which bash
# /usr/bin/bash

which git node
# /usr/bin/git
# /usr/bin/node

Show the resolved path of a symbolic link

realpath ~/www
# /usr/share/nginx/html

Determine the current directory

pwd
# /home/my/current/directory

Devices

Display file system disk space usage with total

Show the file system disk space usage in human readable format.

df -h --total
# Filesystem      Size  Used Avail Use% Mounted on
# devtmpfs        487M     0  487M   0% /dev
# tmpfs           497M     0  497M   0% /dev/shm
# tmpfs           497M  508K  496M   1% /run
# tmpfs           497M     0  497M   0% /sys/fs/cgroup
# /dev/vda1        30G  2.7G   26G  10% /
# tmpfs           100M     0  100M   0% /run/user/0
# total           2.2T  600G  100G  20% -

Display system memory information with total

free -h --total
#               total        used        free      shared  buff/cache   available
# Mem:           200G         60G        100G        262M         30G        180G
# Swap:            0B          0B          0B
# Total:         200G         60G        100G

or

cat /proc/meminfo
# MemTotal:       183815530 kB
# MemFree:        101918660 kB
# MemAvailable:   123712410 kB
# ....

Tip: Pipe grep to filter your results. E.g cat /proc/meminfo | grep MemTotal

Mount a FAT32 USB device

mount -t vfat /dev/sdb1 /media/usb

Increase temporary directory size

mount -o remount,size=5G /tmp/

Find out a block device by label

blkid --label MY_MICROSD
# /dev/sdc1

lsblk --output name,serial,uuid,partuuid,label,partlabel $(blkid --label MY_MICROSD)
# NAME SERIAL UUID          PARTUUID       LABEL        PARTLABEL
# sdc1        4BGE-7510     ec123nba-02    MY_MICROSD

Users and Groups

Switch user and execute command immediately

sudo -Hu root fish

Add an existing user to existing group

usermod -a -G ftp john

Date & Time

Show extended ISO format Date (ISO 8601)

date "+%Y-%m-%dT%H:%m:%S"
# 2018-09-13T10:09:26

Network

Show current IP address

ifconfig | awk '/<UP,BROADCAST,RUNNING,MULTICAST>/ { getline; print $2 }'
# or
ifconfig | grep -E "([0-9]{1,3}\.){3}[0-9]{1,3}" | grep -v 127.0.0.1 | awk '{ print $2 }' | cut -f2 -d: | head -n1

Miscellaneous

Show GNU/Linux distribution and operating system

a) Using hostnamectl:

hostnamectl | grep -E "(.+)(System|Kernel|Arch)(.+)"
#  Operating System: Arch Linux
#            Kernel: Linux 5.1.7-arch1-1-ARCH
#      Architecture: x86-64

b) Using cat /etc/os-release:

cat /etc/os-release
# NAME="Arch Linux"
# PRETTY_NAME="Arch Linux"
# ID=arch
# BUILD_ID=rolling
# ANSI_COLOR="0;36"
# HOME_URL="https://www.archlinux.org/"
# DOCUMENTATION_URL="https://wiki.archlinux.org/"
# SUPPORT_URL="https://bbs.archlinux.org/"
# BUG_REPORT_URL="https://bugs.archlinux.org/"
# LOGO=archlinux

Generate random numbers

a)

od -vAn -N64 < /dev/urandom | tr '\n' ' ' | sed "s/ //g" | head -c 32
# 03121617301002504516642404031105

b)

env LC_CTYPE=C tr -dc "0-9" < /dev/urandom | head -c 32 | xargs
# 50569696992247151969921987764342

Change head value to truncate the result's length.

Generate random alphanumerics

a) Alphanumeric only

base64 /dev/urandom | tr -d '/+' | head -c 32 | xargs
# 3udiq6F74alwcPwXzIDWSnjRYQXcxiyl

b) Alphanumeric with a custom chars set

env LC_CTYPE=C tr -dc "A-Za-z0-9_!@#\$%^&*()-+=" < /dev/urandom | head -c 32 | xargs
# yiMg^Cha=Zh$6Xh%zDQAyBH1SI6Po(&P

Change tr -dc char set to get a custom result.

Generate a random hash

od -vAn -N64 < /dev/urandom | tr '\n' ' ' | sed "s/ //g" | openssl dgst -sha256 | sed "s/-//g"
# 7adf57e0a90b32ce0e1f446268dbd62b583c649a2e71a426519c6e9c0006b143

Openssl digest algorithms supported: md5, md4, md2, sha1, sha, sha224, sha256, sha384, sha512, mdc2 and ripemd160

Generate a random UUID

uuidgen | tr "[:lower:]" "[:upper:]"
# D2DA7D0C-ABAA-4866-9C97-61791C9FEC89

Generate 1 million of unique random phone numbers

This command generate one million of unique random phone numbers (random permutations) fast using GNU/Linux shuf command. Use sed command for customize each number format. For example for add some prefix or suffix. Remember shuf is not limited to numbers only.

shuf -i 100000000-999999999 -n 1