BASH Shell related tutorial/FAQ

Bash check if string starts with character such as #

last updated December 14, 2018 in BASH Shell, Linux, UNIX

My bash shell script read a config file line-by-line using a bash while loop. I need to check if a string stored in $var starts with some value such as # character. If so I need to ignore that value and read the next line from my config file. How do I check if variable begins with # in bash shell scripting running on a Linux or Unix-like operating systems?

Bash get exit code of command on a Linux / Unix

last updated December 4, 2018 in BASH Shell, Linux, UNIX

I am a new Linux system user. How do I get the exit code of a command? How do I get the exit code of Linux or Unix shell command and store it into a shell variable?

Bash read file names from a text file and take action

last updated December 3, 2018 in BASH Shell, Linux, Programming, UNIX

I need to read a list of file names from a text file named input.txt and take action each file name. How do I read file names from a text file and say run /bin/foo command on each file? How do I read filenames from a text file and take certain action on those files?

How to add bash auto completion in RHEL 8 (Red Hat Linux)

last updated November 21, 2018 in BASH Shell, Linux, RedHat and Friends

I set up a new RHEL 8 VM from cloud images, but my auto-completion of bash shell commands are not working. How do I enable autocomplete feature in RHEL 8 (Red Hat Enterprise Linux 8)? How do I write simple bash completion code in RHEL 8?

Bash foreach loop examples for Linux / Unix

last updated November 19, 2018 in BASH Shell, Linux, UNIX

I used foreach on a Unix operating system and csh shell loop. Now, I am a Linux operating system. How do I use foreach loop in bash shell running on Linux?

Bash check if process is running or not on Linux / Unix

last updated November 17, 2018 in BASH Shell, CentOS, Debian / Ubuntu, FreeBSD, Linux, UNIX

I am new to Linux shell scripting. I am using a CentOS 7 Linux and Ubuntu 18.04 LTS server in the cloud. How do I check if a process is running or not on Linux? How do I determine whether a process is running or not in a shell script running on an Ubuntu server?

How to add bash auto completion in Ubuntu Linux

last updated November 21, 2018 in BASH Shell, Linux, Package Management, Ubuntu Linux

I set up a new Ubuntu Linux LXD container, but my auto-completion of bash shell commands are not working. How do I enable autocomplete feature in Ubuntu Linux 18.04 LTS?

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