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How to check that a bash script has exactly two arguments?
For example, if the user enters 1 arg instead of 2 (we need 2 since we’re comparing two directories), it should give an error. If both arg are valid, compare the directories and output to a file. Processing arguments that are passed via a script’s command line is as simple as follows.
How to pass an argument in.sh script?
If I call qsub foo.sh a b the first argument gets correctly processed and echoed to the command line as ‘a’. However, I do not know how to pass an argument in the second case starting with ‘#$ -N’. In this case $2 does not get evaluated to ‘b’ but actually ‘$2’ is set.
How to check the existence of an argument in a script?
The $# variable will tell you the number of input arguments the script was passed. Or you can check if an argument is an empty string or not like: if [ -z “$1” ] then echo “No argument supplied” fi The -z switch will test if the expansion of “$1” is a null string or not.
How to check if two arguments are valid?
If both arg are valid, compare the directories and output to a file. Processing arguments that are passed via a script’s command line is as simple as follows. Say we had this script: You can then check if the arguments, 1 & 2, are valid directories or not, and then bail out or proceed as needed.
Which is the equivalent of a string operator in Bash?
As a string operator, = is equivalent to ==. Also, note the whitespace around = or ==: it’s required. While you can do [ [ 1 == 1 ]] or [ [ $ ( ( 1+1 )) == 2 ]] it is testing the string equality — not the arithmetic equality.
What’s the difference between = and EQ in Bash?
It’s the other way around: = and == are for string comparisons, -eq is for numeric ones. -eq is in the same family as -lt, -le, -gt, -ge, and -ne, if that helps you remember which is which. == is a bash-ism, by the way. It’s better to use the POSIX =. In bash the two are equivalent, and in plain sh = is the only one guaranteed to work.
How to add arguments and options in Bash?
$OPTARG is always the variable name used for each new option argument, no matter how many there are. You must assign the value in $OPTARG to a variable name that will be used in the rest of the program. This new stanza does not have an exit statement.
What are the variables in the bash script?
Bash has a lot of built-in special variables that are quite handy and are available at your disposal. The table below highlights the most common special built-in bash variables: The name of the bash script. The bash script arguments.
How to check if passed argument is file or directory?
#!/bin/bash echo “Please Enter a file name :” read filename if test -f $filename then echo “this is a file” else echo “this is not a file” fi Highly active question. Earn 10 reputation (not counting the association bonus) in order to answer this question.