Linux Shell实用工具

for x in one two three four
do
    echo number $x
done

for x in /var/log/*
do
    echo $(basename $x) is a file living in /var/log
done

for j in $(seq 1 5)
do
    echo $j
done

for (( i=1; i<=5; i++ ))
do
    echo "i=$i"
done

i=1
while [ $i -le 10 ]
do
    echo $i
    i=`expr $i + 1`;
    # let i+=1;
    # ((i++));
    # i=$[$i+1];
    # i=$(( $i + 1 ))
done

i=1
until [ $i -gt 10 ]
do
    echo $i
    i=$(( $i + 1 ))
done

sed 's/src/dst/flags' fname > fname.sed

1: echo "123 abc" | sed 's/[0-9]*/& &/'    # 123 123 abc
2: echo "abc 123" | sed 's/[0-9]*/& &/'    # abc 123
3: echo "abc 123" | sed -E 's/[0-9]+/& &/' # abc 123 123

echo hello123 | sed -E 's/([a-z]*).*/\1/'               # hello
echo hello world | sed -E 's/([a-z]+) ([a-z]+)/\2 \1/'  # world hello
echo hello hello world | sed -E 's/([a-z]+) \1/\1/'     # hello world

echo 1b 2b 3b 4b | sed -E 's/b/?/3'     # 1b 2b 3? 4b
echo 1b 2b 3b 4b | sed -E 's/b/?/3g'    # 1b 2b 3? 4?

sed -nE '10,20 p'                       # print line 10-20
sed -nE '10,20 !p'                      # print line not in 10-20
sed -nE '/^#/ s/[0-9]+//gp'             # del num in #line
sed -nE '10,/^#/ s/[0-9]+//gp'          # del num from 10line to #line
sed -nE '10,/^#/ d'                     # del line from 10line to #line
sed -nE '10,/^#/ !d'                    # del line not in 10line to #line

# Windows line to Unix(remove ^M)
sed -i 's/\r//' fname

# upper to lower
sed 'y/ABCDEFGHIJKLMNOPQRSTUVWXYZ/abcdefghijklmnopqrstuvwxyz/' fname

# grep line begin with cp or scp
sed -n '/^s*cp / p' fname
sed -n '/^s*cp / =' fname                       # print line-number only

# delete line begin with cp or scp
sed -n '/^s*cp / d' fname

# del begin whitespace in line
sed -i 's/^[ \t]*//g' fname

# del trailing whitespace in line
sed -i 's/[ \t]*$//g' fname

echo world | sed '/world/ i\hello '             # insert before world-line
echo world | sed '/world/ a\hello \nend'        # append after world-line
echo world | sed '/world/ c\hello '             # change line to hello-line
ls -lF | sed -nE '/^total\ |.*\/$/ !p'          # show file except directory

#!/bin/bash

fname=$1
function del_cpp_comment()
{
    # del //... in line begin
    sed -i '/^[ \t]*\/\// d' $fname

    # del //... in line end
    sed -i "s/[ \t]*\/\/[^\"]*$//" $fname

    # del single line only have /*...*/
    sed -i '/^[ \t]*\/\*.*\*\/[ \t]*$/ d' $fname

    # del single line /*...*/
    sed -i 's/[ \t]*\/\*.*\*\///' $fname

    # del multi line /*...*/
    sed -i '/^[ \t]*\/\*/,/.*\*\// d' $fname
}
del_cpp_comment

top -hv|-bcHiOSs -d secs -n max -u|U user -p pid -o fld -w [cols]

$ free
             total       used       free     shared    buffers     cached
Mem:       5998076    5771648     226428     437208     372552    3365820
-/+ buffers/cache:    2033276    3964800
Swap:      7916540     263972    7652568

vmstat [options] [delay [count]]

mpstat [-A] [-u] [-V] [-I {SUM|CPU|SCPU|ALL}] [-P {cpu [,...]|ON|ALL}] [interval[count]]

find . -type f -print0 | xargs -0 echo
find . -type f -print0 | xargs -0 -n 1 echo

find . -type f -exec echo '{}' +
find . -type f -exec echo '{}' \;

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
6e:45:f9:a8:af:38:3d:a1:a5:c7:76:1d:02:f8:77:00.
Please contact your system administrator.
Add correct host key in /home/XX/.ssh/known_hosts to get rid of this message.
Offending RSA key in /var/lib/sss/pubconf/known_hosts:4
RSA host key for pong has changed and you have requested strict checking.
Host key verification failed.

ssh-keygen -R hostname
ssh-keygen -R [23.34.56.76]:26          # 指定端口的格式

StrictHostKeyChecking no                # 避免询问加入known_host