It’s a convention, but a particularly useful one when you think about it. In general, if a program succeeds that’s all you need to know. If it fails, however, you might need to know all kinds of information about the failure – why it happened, how to fix it, etc. Having zero mean ‘success’ and … Read more
grep -a It can’t get simpler than that.
This works in bash and zsh, tested on Linux and OS X: sed ‘s/regexp/\’$’\n/g’ In general, for $ followed by a string literal in single quotes bash performs C-style backslash substitution, e.g. $’\t’ is translated to a literal tab. Plus, sed wants your newline literal to be escaped with a backslash, hence the \ before … Read more
diff(1) is not the answer, but comm(1) is. NAME comm – compare two sorted files line by line SYNOPSIS comm [OPTION]… FILE1 FILE2 … -1 suppress lines unique to FILE1 -2 suppress lines unique to FILE2 -3 suppress lines that appear in both files So comm -2 -3 file1 file2 > file3 The input files … Read more
Use nohup if your background job takes a long time to finish or you just use SecureCRT or something like it login the server. Redirect the stdout and stderr to /dev/null to ignore the output. nohup /path/to/your/script.sh > /dev/null 2>&1 &
Use awk with a flag to trigger the print when necessary: $ awk ‘/abc/{flag=1;next}/mno/{flag=0}flag’ file def1 ghi1 jkl1 def2 ghi2 jkl2 How does this work? /abc/ matches lines having this text, as well as /mno/ does. /abc/{flag=1;next} sets the flag when the text abc is found. Then, it skips the line. /mno/{flag=0} unsets the flag … Read more
This error can mean that ./arm-mingw32ce-g++ doesn’t exist (but it does), or that it exists and is a dynamically linked executable recognized by the kernel but whose dynamic loader is not available. You can see what dynamic loader is required by running ldd /arm-mingw32ce-g++; anything marked not found is the dynamic loader or a library … Read more
The send-prefix command can be used to send your prefix keystroke to (the process running in) the active pane. By default, the prefix is C-b and C-b is bound to send-prefix (so that hitting it twice sends a single C-b to the active pane). This is just what we need to access the bindings of … Read more
$$ is the process ID (PID) in bash. Using $$ is a bad idea, because it will usually create a race condition, and allow your shell-script to be subverted by an attacker. See, for example, all these people who created insecure temporary files and had to issue security advisories. Instead, use mktemp. The Linux man … Read more
For the cut(1) man page: Use one, and only one of -b, -c or -f. Each LIST is made up of one range, or many ranges separated by commas. Selected input is written in the same order that it is read, and is written exactly once. It reaches field 1 first, so that is printed, … Read more