05-E.8.2: File Output Manipulation - xargs
- Page ID
- 32560
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)The xargs Command
xargs is a Unix command which can be used to build and execute commands from standard input.
Importance :
Some commands like grep can accept input as parameters, but some commands accepts arguments. This is where xargs came into the picture.
Syntax :
xargs [ OPTIONS ] [command]
xargs Command Options
| Options | Option Meaning |
|---|---|
| 0 | Input items are terminated by null character instead of white spaces. |
| -a file | Read items from file instead of standard input. |
| –delimiter = delim | Input items are terminated by a special character. |
| -E eof-str | Set the end of file string to eof-str. |
| -I replace-str | Replace occurrences of replace-str in the initial arguments with names read from standard input. |
| -L max-lines | Use at-most max-lines non-blank input lines per command line. |
| -p | Prompt the user about whether to run each command line and read a line from terminal. |
| -r | If the standard input does not contain any nonblanks, do not run the command. |
| -x | Exit if the size is exceeded. |
| –help | Print the summary of options to xargs and exit. |
| –version | Print the version no. of xargs and exit. |
Simply put xargs takes each input and applies the command to that input. Below are some examples of xargs:
# the file states.list contains 3 names, we cat the file and pipe the output to xargs mkdir - xargs # takes each line from the file and uses it as an argument to mkdir pbmac@pbmac-server $ cat states.list Alabama Wyoming Washington pbmac@pbmac-server $ cat states.list | xargs mkdir pbmac@pbmac-server $ ls Alabama states.list Washington Wyoming # now we use find, searching for type d (directory) and send all the output to xargs rmdir # the error message is becasue the find command also finds the . directory - the directory where we currently are pbmac@pbmac-server $ find . -type d | xargs rmdir rmdir: failed to remove '.': Invalid argument pbmac@pbmac-server $ ls pbmac@pbmac-server $ # there are 3 files ending in .txt, using the find command we pipe the output of the find to xzargs rm to remove # each .txt file. pbmac@pbmac-server $ ls one.txt states.list three.txt two.txt pbmac@pbmac-server $ find . -name "*.txt" | xargs rm pbmac@pbmac-server $ ls states.list
Adapted from:
"xargs command in Linux with examples" by Mandeep Singh, Geeks for Geeks is licensed under CC BY-SA 4.0