The standard warnings regarding use of tcsh/csh apply (don’t use it for scripting, due to its inherent limitations), but here’s the translation: if ( “$1” == “” ) then # parentheses not strictly needed in this simple case echo “variable is empty” else echo “variable contains $1” endif Note, though, that if you were to … Read more
Aliases are shell-specific – in this case, most likely bash-specific. To execute an alias, you need to execute bash, but aliases are only loaded for interactive shells (more precisely, .bashrc will only be read for an interactive shell). bash -i runs an interactive shell (and sources .bashrc). bash -c cmd runs cmd. Put them together: … Read more
Find all the symbolic links in a directory: ls -l `find /usr/bin -maxdepth 1 -type l -print` For the listing of hidden files: ls -ald .*
In the usual Windows command prompt (i.e. cmd.exe), just using call mybat.bat did what I wanted. I got all the environment variables it had set.
In csh, you can either try env: % env LD_LIBRARY_PATH=/foo/bar myprogram or, a subshell: % (setenv LD_LIBRARY_PATH /foo/bar; myprogram)
Assuming you are on a linux, the following should work: cat /dev/urandom | tr -cd ‘a-f0-9’ | head -c 32 This is only pseudo-random if your system runs low on entropy, but is (on linux) guaranteed to terminate. If you require genuinely random data, cat /dev/random instead of /dev/urandom. This change will make your code … Read more
Take a look at the various test operators (this is for the test command itself, but the built-in BASH and TCSH tests are more or less the same). You’ll notice that -x FILE says FILE exists and execute (or search) permission is granted. BASH, Bourne, Ksh, Zsh Script if [[ -x “$file” ]] then echo … Read more
Use the “dot space script” calling syntax. For example, here’s how to do it using the full path to a script: . /path/to/set_env_vars.sh And here’s how to do it if you’re in the same directory as the script: . set_env_vars.sh These execute the script under the current shell instead of loading another one (which is … Read more
This depends on what shell you are using. If you are using bash, then the ulimit command controls several settings relating to program execution, such as whether you should dump core. If you type ulimit -c unlimited then that will tell bash that its programs can dump cores of any size. You can specify a … Read more
Try linux command chsh. The detailed command is chsh -s /bin/bash. It will prompt you to enter your password. Your default login shell is /bin/bash now. You must log out and log back in to see this change. The following is quoted from man page: The chsh command changes the user login shell. This determines … Read more