1. Check Empty String 1 2 3 4 5 6 1. 2. 3. 4. 5. 6. if [[ -z "$emptyString" ]]then echo "Empty"else echo "Not Empty"fi 1. Here is a reference material from Stackoverflowhttp://stackoverflow.com/questions
-r file True if file exists and is readable. -s file True if file exists and has a size greater than zero. -t fd True if file descriptor fd is open and refers to a terminal. -u file True if file exists and its set-user-id bit is set. ...
-O filename True if file exists and is owned by the effective user id. -r filename Check if file is a readable -S filename Check if file is socket -s filename Check if file is nonzero size -u filename Check if file set-ser-id bit is set -w filename Check if file is writabl...
#文件测试操作-d FILE_NAM # TrueifFILE_NAM is a directory-e FILE_NAM # TrueifFILE_NAM exists-f FILE_NAM # TrueifFILE_NAM existsandis a regular file-r FILE_NAM # TrueifFILE_NAM is readable-s FILE_NAM # TrueifFILE_NAM existsandisnotempty...
bash will use whatever regex engine is installed on the user's system. Stick to POSIX regex features if aiming for compatibility.CAVEAT: This example only prints the first matching group. When using multiple capture groups some modification is needed....
file exists. After reading that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile, in that order, and reads and executes commands from the first one that exists and is readable. The --noprofile option may be used when the shell is started to inhibit ...
-r file If file exists and is readable. -s file If file exists and its size is greater than zero. -t fd If file descriptor is open and refers to a terminal. -u file If file exists and its set-user-id bit is set. -w file If file exists and is writable. -x file If file ex...
Now let’s perform a similar check,but with thetest [command: $ if [ -x a.out ]; then echo "File is executable"; else echo "File is not executable"; fi File is executable So, thetest‘sxflag proves if the file exists and is executable. ...
Similarly for example we can use while loop to check if file does not exists. This script will sleep until file does exists. Note bash negator "!" which negates the -e option. #!/bin/bash while [ ! -e myfile ]; do # Sleep until file does exists/is created ...
3. File and Directory Checks: -e: Exists -f: Regular file -d: Directory -r: Readable -w: Writable -x: Executable Example of using If Statement: Let’s illustrate the usage of if statements with a few examples: Example 1: Numeric Comparison ...