You can pipe the script’s output through a loop that prefixes the current date and time: ./script.sh | while IFS= read -r line; do printf ‘%s %s\n’ “$(date)” “$line”; done >>/var/log/logfile If you’ll be using this a lot, it’s easy to make a bash function to handle the loop: adddate() { while IFS= read -r … Read more
I have a little script that extracts archives, I found it somewhere on the net: extract () { if [ -f $1 ] ; then case $1 in *.tar.bz2) tar xvjf $1 ;; *.tar.gz) tar xvzf $1 ;; *.bz2) bunzip2 $1 ;; *.rar) unrar x $1 ;; *.gz) gunzip $1 ;; *.tar) tar xvf $1 … Read more
The best method is to start the process in a terminal multiplexer. Alternatively you can make the process not receive the HUP signal. A terminal multiplexer provides “virtual” terminals which run independent from the “real” terminal (actually all terminals today are “virtual” but that is another topic for another day). The virtual terminal will keep … Read more
Avoid using /etc/mtab because it may be inconsistent. Avoid piping mount because it needn’t be that complicated. Simply: if grep -qs ‘/mnt/foo ‘ /proc/mounts; then echo “It’s mounted.” else echo “It’s not mounted.” fi (The space after the /mnt/foo is to avoid matching e.g. /mnt/foo-bar.)
command 2> >(while read line; do echo -e “\e[01;31m$line\e[0m” >&2; done)
This can be easily done with temporary named pipes: bash –init-file <(echo “ls; pwd”) Credit for this answer goes to the comment from Lie Ryan. I found this really useful, and it’s less noticeable in the comments, so I thought it should be its own answer.
You can turn off history substitution using set +H.
Bash has a “loadable” sleep which supports fractional seconds, and eliminates overheads of an external command: $ cd bash-3.2.48/examples/loadables $ make sleep && mv sleep sleep.so $ enable -f sleep.so sleep Then: $ which sleep /usr/bin/sleep $ builtin sleep sleep: usage: sleep seconds[.fraction] $ time (for f in `seq 1 10`; do builtin sleep 0.1; … Read more
One of the tricks I follow is to put # in the beginning while using the rm command. root@localhost:~# #rm -rf / This prevents accidental execution of rm on the wrong file/directory. Once verified, remove # from the beginning. This trick works, because in Bash a word beginning with # causes that word and all … Read more
Supposing your array is $errors, just check to see if the count of elements is zero. if [ ${#errors[@]} -eq 0 ]; then echo “No errors, hooray” else echo “Oops, something went wrong…” fi