Contents
- 1 Why does my shell script choke on whitespace or other special?
- 2 Do you have to read input from stdin in tcsh?
- 3 When do you use parentheses in tcsh shell?
- 4 When is double quoting necessary in bash script?
- 5 What does it mean to split a variable in Bash?
- 6 When is double quoting necessary in zsh shell?
Why does my shell script choke on whitespace or other special?
If you write myfiles=”file1 file2″, with spaces to separate the files, this can’t work with file names containing spaces. Unix file names can contain any character other than / (which is always a directory separator) and null bytes (which you can’t use in shell scripts with most shells).
Do you have to read input from stdin in tcsh?
Since the tcsh shell doesn’t include a read statement like the bash shell, you must read an input value directly from STDIN. You do this using the $symbol: After retrieving the input, the switch statement compares the text to each case statement.
When do you use parentheses in tcsh shell?
In the tcsh shell, you just need to use parentheses to perform any mathematical function. However, you can only perform mathematical operations using the at symbol alias of the set command:
Which is the if statement in tcsh scripting?
The if statements. The tcsh if statement can use one of several formats. The first format looks like this: if (expression) command. If the expression defined in the parentheses evaluates to a TRUE condition, the shell executes the command listed on the line: $ cat test3. #!/bin/tcsh.
How to express a new line in Bash?
Just include an actual newline inside the quotes (this works with either single or double quotes). Note that if the second line is indented, the spaces are part of the string. Furthermore always use double quotes around variable substitutions.
When is double quoting necessary in bash script?
This answer applies to Bourne/POSIX-style shells ( sh, ash, dash, bash, ksh, mksh, yash …). Zsh users should skip it and read the end of When is double-quoting necessary? instead.
What does it mean to split a variable in Bash?
It means something much more complex: First, take the value of the variable. Field splitting: treat that value as a whitespace-separated list of fields, and build the resulting list. For example, if the variable contains foo * bar then the result of this step is the 3-element list foo, *, bar.
When is double quoting necessary in zsh shell?
Zsh users should skip it and read the end of When is double-quoting necessary? instead. If you want the whole nitty-gritty, read the standard or your shell’s manual. Note that the explanations below contains a few approximations (statements that are true in most conditions but can be affected by the surrounding context or by configuration).