Shell tricks

I put any tricks I pick up with shells here, as they are easy to forget.

1 Shell tricks

1.1 Recursive grep
1.2 Too many files
1.3 Split string
1.4 Find/Replace multiple files with Perl
1.5 Cool prompt

Recursive grep

GNU grep has a silly -R switch. Don't use it, use find:

find . -type f -exec grep "mysearch" /dev/null {} \;

Too many files

$ rm *
pdksh: rm: Argument list too long

Can be easily fixed with:

for i in `ls`; do rm $i; done

Split string

Use a for loop and set the variable IFS to the separator.

#!/bin/sh

IFS=:
for dir in $PATH; do
    if [ -x $dir/gcc ];then
        GCC=$dir/gcc;
        break;
    fi
done

The above searches through the path for the location of the executable gcc.

Find/Replace multiple files with Perl

perl -pi -e "s/find/replace/g" file1 file2 ...

This one liner runs the given regex over the specified files, modifying the files inline. No backups are made for you.

Cool prompt

I picked this up on the internet, but sadly I can't remember where. Kudos to whoever put the effort into the colours. Put it in your .profile:

# cool prompt
if type -p printf > /dev/null 2>&1; then
    red=$(printf '\e[31m')
    colors="\[\e[0;36m\]\w\[\e[01m\]\[\e[0m\]"
    export PS1="${NAME}:${colors}$([ $? -eq 0 ]||printf $red)\$\[\e[0m\] "
else
    export PS1='\[\e[0;36m\]\w\[\e[01m\]\[\e[0m\]\$\[\e[0m\] \$'
fi