Bash supports for loop with three parts like other standard programming languages. The first part contains initialization, the second part contains the termination condition and the third part contains increment or decrement operation. This loop is mainly used when the number of iteration is previously...
The result of bash's regex matching can be used to replace sed for a large number of use-cases.CAVEAT: This is one of the few platform dependent bash features. bash will use whatever regex engine is installed on the user's system. Stick to POSIX regex features if aiming for ...
The glob term refers to recognizing text as a pattern followed by expanding matching filenames. Let’s take a look at perhaps the most common example: $ for file in *; do echo $file; done The star symbol is expanded to a list filled with the names of all files in the current direct...
Loop over an array with an index Loop over the contents of a file Loop over files and directoriesFILE HANDLING Read a file to a string Read a file to an array (by line) Get the first N lines of a file Get the last N lines of a file Get the number of lines in a file Count ...
1. bash builtin commands(fedora38-GNU Bash 5.2) BASH_BUILTINS(1) General Commands Manual BASH_BUILTINS(1)23NAME4:, ., [, alias, bg, bind, break, builtin, caller, cd, command, compgen, complete, compopt, continue, declare, dirs, disown,echo,5enable, eval, exec, exit, export,false...
Case statements are particularly useful when dealing with pattern matching or regular expressions. To demonstrate, take a look at the followingchar.shbash script: #!/bin/bash CHAR=$1 case $CHAR in [a-z]) echo "Small Alphabet." ;;
More complex shell commands are composed of simple commands arranged together in a variety of ways: in a pipeline in which the output of one command becomes the input of a second, in a loop or conditional construct, or in some other grouping. ...
If for example you want to create a user for every username provided to the command-line, you can use the for loop to that effect. #!/bin/bash for USERNAME in ${@} do echo "Created username ${USERNAME}" done Awesome! You know how you can iterate over the argument list provided to...
${parameter%word} ${parameter%%word} The word is expanded to produce a pattern just as in pathname expansion. If the pattern matches a trailing portion of the value of parameter, then the expansion is the value of parameter with the shortest matching pattern deleted (the ``%'' case) or ...
Beware of globbing if there might be no matches with the pattern (and this is often the case). By default, if a glob like./*.pdfmatches no files, then the original glob pattern will be returned instead. This is almost never what you want. E.g., in a “for” loop this will cause...