10 Essential UNIX Command-Line Habits to Boost Your Efficiency

Introduction

The article introduces ten useful UNIX command‑line habits that help users break bad patterns, improve speed, and reduce errors when working in the shell.

1. Create directory trees in a single command

Bad habit: creating each level of a directory hierarchy with separate mkdir calls.

~ $ mkdir tmp
~ $ cd tmp
~ $ mkdir a
~ $ cd a
~ $ mkdir b
~ $ cd b
~ $ mkdir c

Good habit: use the -p option to create the entire tree at once. ~ $ mkdir -p tmp/a/b/c Complex trees can be built with brace expansion:

~ $ mkdir -p project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a}

On systems lacking -p, the mkdirhier script provides equivalent functionality.

~ $ mkdirhier project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a}

2. Change directory with -C instead of moving archives

Instead of moving a .tar file to the target directory before extraction, use the -C option of tar to specify the extraction directory directly.

~ $ tar xvf -C tmp/a/b/c newarc.tar.gz

3. Combine commands with control operators

Use && to run a second command only if the first succeeds, and || to run a second command only if the first fails. ~ $ cd tmp/a/b/c && tar xvf ~/archive.tar Another example using both operators:

~ $ cd tmp/a/b/c || mkdir -p tmp/a/b/c && tar xvf -C tmp/a/b/c ~/archive.tar

4. Quote variables carefully

Always enclose variable expansions in double quotes unless you have a specific reason not to. When concatenating a variable with alphanumeric text, use braces to avoid accidental merging.

~ $ VAR="tmp/*"
~ $ echo "$VAR"tmp/*
~ $ echo "${VAR}a"tmp/*a

5. Use escape sequences for long input

Backslashes ( \) let you split long commands over multiple lines while the shell treats them as a single line.

~ $ cd tmp/a/b/c || \>
    mkdir -p tmp/a/b/c && \>
    tar xvf -C tmp/a/b/c ~/archive.tar

6. Group commands in lists

Use a subshell ( ( … )) to run a list of commands in a separate shell, allowing redirection of the whole group.

~ $ ( cd tmp/a/b/c || mkdir -p tmp/a/b/c && \
    VAR=$PWD; cd ~; tar xvf -C $VAR archive.tar ) \
    | mailx admin -S "Archive contents"

Alternatively, use braces ( { …; }) to run a list in the current shell.

~ $ { cp ${VAR}a . && chown -R guest.guest a && \>
    tar cvf newarchive.tar a; } | mailx admin -S "New archive"

7. Use xargs outside find

Pipe the output of find (or any list) to xargs to build command lines with the listed items as arguments.

~ $ find . -name "*.log" | xargs grep "ERROR"

xargs

can also reformat whitespace‑separated lists or feed filenames to other tools.

~ $ ls -1 | xargs -I{} echo "File: {}"

8. Let grep count with -c when appropriate

Using grep -c is faster than piping grep to wc -l:

~ $ time grep and tmp/a/longfile.txt | wc -l
real    0m0.097s
~ $ time grep -c and tmp/a/longfile.txt
real    0m0.013s

For counting pattern instances, combine grep -o with wc -l:

~ $ grep -o and tmp/a/longfile.txt | wc -l

9. Match specific fields with awk instead of grep

When you need to filter on a particular column, awk is more precise than grep.

~ $ ls -l | awk '$6 == "Dec"'

10. Avoid piping cat into grep

grep

can read files directly, so using cat adds unnecessary overhead.

~ $ time cat tmp/a/longfile.txt | grep and
real    0m0.015s
~ $ time grep and tmp/a/longfile.txt
real    0m0.010s

Conclusion

Review your shell habits and replace the listed bad patterns with the recommended practices. Adopting these ten habits will make your UNIX command‑line work faster, safer, and more maintainable.