The shell is unix's command-line interface. You can type commands in a shell interactively, or write scripts to automate tasks. Use this tag for questions applying to /bin/sh and most compatible shells (ash, bash, ksh, zsh, …).

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29
votes
7answers
2k views

How to determine where an environment variable came from

I have a linux instance that I set up some time ago. When I fire it up and log in as root there are some environment variables that I set up but I can't remember or find where they came from. I've ...
19
votes
6answers
752 views

How could I remember how to use redirection?

I know what program > /dev/null 2>&1 does. It redirects the output to /dev/null and 2>&1 means to redirect the error output in the same place where the output is sent. My ...
9
votes
1answer
806 views

How do I get a long listing for a single directory?

I want to see a long listing for a single directory. When I type ls -lha, I see this: drwxrwxr-x 4 username groupname 4.0K 2010-08-05 09:55 files drwxrwxr-x 7 username groupname 4.0K 2010-08-05 ...
11
votes
4answers
475 views

rolling diffs for storage of highly similar files?

At work we do a nightly dump of our mysql databases. From day to day, I would guestimate that close to 90-95% of the data is duplicate, increasing as time goes on. ( Heck at this point some are ...
37
votes
5answers
52k views

How to monitor CPU/memory usage of a single process?

I would like to monitor one process's memory / cpu usage in real time. Similar to top but targeted at only one process, preferably with a history graph of some sort.
18
votes
4answers
6k views

make my zsh prompt show mode in vi mode

I use bindkey -v (for bash-ers set -o vi I think that works in zsh too) or vi(m) mode. but it bugs me that I don't have any visual cue to tell me whether I'm in insert mode or command mode. Does ...
41
votes
12answers
10k views

best way to search my shell's history

Is there a better way to search my history file for a command than grep? I do have some idea what the command starts as, but I don't know how far back in the history it is. update: was formerly zsh ...
12
votes
7answers
2k views

Practical tasks to learn shell scripting

I'm looking for some common problems in unix system administration and ways that shell scripting can solve them. Completely for self-educational purposes. Also I'd like to know how would you go about ...
20
votes
1answer
5k views

The 'less' command-line equivalent of 'tail -f'

I would like to open up a file using less, and have it automatically scroll the file similar to tail -f. I know that I can do less file, and then hit Shift-F to forward forever; like tail -f. I need ...
15
votes
5answers
5k views

Unix equivalent of PowerShell?

I've always found it awkward when complex shell commands involve parsing text output with AWK. Basically we're converting structured data into text, then parsing the text again to get back at the ...
73
votes
6answers
44k views

Allow setuid on shell scripts

The setuid permission bit tells Linux to run a program with the effective user id of the owner instead of the executor: > cat setuid-test.c #include <stdio.h> #include <unistd.h> int ...
98
votes
11answers
121k views

Colorizing your terminal and shell environment?

I spend most of my time working in Unix environments and using terminal emulators. I try to use color on the command line, because color makes the output more useful and intuitive. What options exist ...
10
votes
3answers
289 views

Which less popular shells do you use and what are their advantages? [closed]

Apart from what you can (arguably?) call the more popular shells (bash, csh, Korn, zsh) what other ones do you know and use and what unique features do they have? ps - One answer per shell would be ...
5
votes
1answer
313 views

What is Linux for VMS DCL “ON ERROR”?

Using VMS DCL command scripts one can catch errors by using the on error command: $ on error then goto MyErrorHandler $ directory samiam.txt $ delete x.txt $ exit $MyErrorHandler: $ print ...
144
votes
10answers
51k views

Turn off buffering in pipe

I have a script which calls two commands: long_running_command | print_progress The long_running_command prints a progress but I'm unhappy with it. I'm using print_progress to make it more nice ...
2
votes
2answers
1k views

What is Linux for $DECK and $EOD?

In VMS DCL one may embed data in a command file using $DECK and $EOD. What is Linux for this?