/bin/bash # Script to see if the variable holds value or not var1=" " var2=linuxtechi if [ -n $var1 ] then echo "string is not empty" else echo "string provided is empty" fi 这里我们只使用 -n 参数,但我们也可以使用 -z,唯一的区别是:使用 -z 时,它搜索长度为零的字符串,而使用...
/bin/bash # Script to see if the variable holds value or not var1=" " var2=linuxtechi if [ -n $var1 ] then echo "string is not empty" else echo "string provided is empty" fi 这里我们只使用 -n 参数,但我们也可以使用 -z,唯一的区别是:使用 -z 时,它搜索长度为零的字符串,而使用...
In bash programming, one of the most common controlling construct is theifstatement. It lets us choose from different courses of action by comparing variables. In this tutorial, we’re going to learn how to negate such conditions in bash, concentrating on the number and string comparison. 2. ...
Bash string comparison It is advisable always to check and compare if two strings are equal in a Bash script; this is quite important for different reasons. If two strings are equal in a Bash script, it implies that both strings have the same length and character sequence. The “if” stat...
-n is one of the supported bash string comparison operators used for checking null strings in a bash script. When -n operator is used, it returns true for every case, but that’s if the string contains characters. On the other hand, if the string is empty, it won’t return true. ...
To enforce this behavior, we can include a check at the beginning of the script using a string comparison: $ cat source_header.sh #!/bin/sh # This script should be sourced rather than executed [[ "$0" = "${BASH_SOURCE[0]}" ]] || { echo "Error: This script should be sourced ...
/bin/bash # arith-loop: script to demonstrate arithmetic operators finished=0 a=0 printf "a\ta**2\ta**3\n" printf "=\t===\t===\n" until ((finished)); do b=$((a**2)) c=$((a**3)) printf "%d\t%d\t%d\n" $a $b $c (...
/bin/bash # loan-calc : script to calculate monthly loan payments PROGNAME=$(basename $0) usage () { cat <<- EOF Usage: $PROGNAME PRINCIPAL INTEREST MONTHS Where: PRINCIPAL is the amount of the loan. INTEREST is the APR as a number (7% = 0.07)....
Towards the beginning of this BASH script are a set of variables with empty strings: ... CL_INSTALLER_PASSWORD='' CL_INSTALLER_HASHED_PASSWORD='' CL_INSTALLER_LICENSE='' CL_INSTALLER_INTERFACES_FILENAME='' CL_INSTALLER_INTERFACES_CONTENT='' CL_INSTALLER_ZTP_FILENAME='' CL_INSTALLER_QUIET=...
ShellCheck - A shell script static analysis tool ShellCheck is a GPLv3 tool that gives warnings and suggestions for bash/sh shell scripts: The goals of ShellCheck are To point out and clarify typical beginner's syntax issues that cause a shell to give cryptic error messages. ...