Yeah, yeah, the question is over a year old, but maybe I can add something useful: How to cron something at a random offset 20 times a day between 9am and 11pm? That’s kinda tricky within cron, because you are dividing 14 hours by 20 execution times. I don’t like the other answers very much … Read more
This should work: #!/bin/bash if [ “$#” -eq 0 ] || [ “$#” -gt 1 ] ; then echo “hello” fi I’m not sure if this is different in other shells but if you wish to use <, >, you need to put them inside double parenthesis like so: if ((“$#” > 1)) …
The POSIX-shell (sh) counterpart of $BASH_SOURCE is $0. see bottom for background info Caveat: The crucial difference is that if your script is being sourced (loaded into the current shell with .), the snippets below will not work properly. explanation further below Note that I’ve changed DIR to dir in the snippets below, because it’s … Read more
/bin/sh is usually some other shell trying to mimic The Shell. Many distributions use /bin/bash for sh, it supports source. On Ubuntu, though, /bin/dash is used which does not support source. Most shells use . instead of source. If you cannot edit the script, try to change the shell which runs it.
grep -v -x -f f2 f1 should do the trick. Explanation: -v to select non-matching lines -x to match whole lines only -f f2 to get patterns from f2 One can instead use grep -F or fgrep to match fixed strings from f2 rather than patterns (in case you want remove the lines in a … Read more
bash looks at the value of $argv[0] (bash is implemented in C) to determine how it was invoked. Its behavior when invoked as sh is documented in the manual: If Bash is invoked with the name sh, it tries to mimic the startup behavior of historical versions of sh as closely as possible, while conforming … Read more
Signals by default are handled by the kernel. Old Unix systems had 15 signals; now they have more. You can check </usr/include/signal.h> (or kill -l). CTRL+C is the signal with name SIGINT. The default action for handling each signal is defined in the kernel too, and usually it terminates the process that received the signal. … Read more
Exporting the function should do it (untested): export -f echo_var seq -f “n%04g” 1 100 | xargs -n 1 -P 10 -I {} bash -c ‘echo_var “$@”‘ _ {} You can use the builtin printf instead of the external seq: printf “n%04g\n” {1..100} | xargs -n 1 -P 10 -I {} bash -c ‘echo_var “$@”‘ … Read more
Addressing the question as updated. #…part of script without redirection… { #…part of script with redirection… } > file1 2>file2 # …and others as appropriate… #…residue of script without redirection… The braces ‘{ … }’ provide a unit of I/O redirection. The braces must appear where a command could appear – simplistically, at the start … Read more
you can for example remove all other chars and count the whats remains, like: var=”text,text,text,text” res=”${var//[^,]}” echo “$res” echo “${#res}” will print ,,, 3 or tr -dc ‘,’ <<<“$var” | awk ‘{ print length; }’ or tr -dc ‘,’ <<<“$var” | wc -c #works, but i don’t like wc.. 😉 or awk -F, ‘{print NF-1}’ … Read more